Modifying & Tuning the BMW 335i

"Best tuning mods for our car of the year (BMW 335i) revealed"

It won many accolades and awards, including our best project car of the year in 2021, and is still regarded by many as the finest BMW around.

What other cars can handle 800hp on stock internals? What other car will still provide an easy way to gain 100hp with relatively simple cost effective mods and upgrades.

If you are new to the 335i and considering which version to buy see our 335i buyers guide. The 335i was the performance version of the BMW 3 Series that remained in production between the years 2005 and 2011.

Let's see what are the best upgrades and mods for this awesome car, so you can turn it from the Ultimate Drivers Car into Your Ultimate Dream Drivers Car.

Please watch my video overview and tips on BMW Tuning. Be sure to keep up with our latest YouTube content and subscribe.

The vehicle was particularly famous among car enthusiasts due to its great 0 to 60 mph times however enthusiasts around the world have modified thousands of vehicles of this series and if you are looking to modify and tune your BMW 335i, this article is all you need. We chose the 335i as our 2021 car of the year 2021 lets look at mods for it.

335i Tuning Guide

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

Best Engine Tuning Mods for your 335i

  1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  3. Upgrades to turbochargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  4. LSD - a limited-slip differential will help get the power down and improve cornering and off the line acceleration
  5. Spark Plugs & ignition coil - making sure you have a good strong spark, a tuned 335i has often been stymied with poor quality ignition.
  6. Intercooler - rather than provide power it maintains your maximum power for longer, and in some cases this can mean over 30hp
  7. Suspension mods - a set of coilovers and better spec suspension will greatly improve your handling

Two 335i Different Engine Options

The BMW 335i sported two different engine options which included

N54 Engine Tuning

The 335i model was particularly famous as it featured the world-famous N54 engine which was a twin-turbocharged straight-six gasoline engine.

It was a successor to the N53 and was introduced in 2006 at the Geneva Motor Show and was instantly loved by aficionados for its great output numbers.

The engine gained so much fame that it remained in production for a decade until 2016 when the company finally decided to discontinue its production.

It is worth mentioning that the phasing out of the N54 had already begun in 2009 when the N55, its successor, was launched.

Engine Displacement & Material

The N54 had a 3 liter displacement. The block and head’s material was Aluminum unlike the magnesium alloy material used in the block and head of the N53.

The N54 was based on the BMW M54 engine, which was made of the same material. The valve train of the engine was DOHC with VVT.

The N54 engine was offered in a wide array of power options and was thus offered in different BMW Series vehicles. The E9x series, including the BMW 335i, had the 311 bhp variant for the model years 2006 to 2010.

Major Problems In The N54

A major problem observed in the N54 especially in the North American market included the failure of the High-Pressure Fuel Pump (HPFP). As a result, the automaker had to make recalls, suffered from lawsuits and thus offered extended warranties.

Several customers claimed that the failure of the High-Pressure Fuel Pumps in their vehicles caused the engine to stop altogether which immediately cut the power of the engine.

Although no major accidents or casualties were reported due to this failure, several near misses on highways have been reported in the past.

Common Fault In The N54 IRF644 MOSFET

A common cause of misfiring and rough engine operation is the N54 MSD80 ECU IRF644 MOSFET which fails frequently.

The part is extremely cheap and costs around $3 only but you will need to buy a set of 6, you can replace it on your own as a DIY project for fixing your car.

Turbo Upgrade Options For the N54

Although the stock N54 engine provided decent performance, still if you want to go further, various options exist in the market. One effective method is going for a turbo upgrade. The stock turbo is known as TD03.

Availability will vary depending on your region and there are plenty of other options around, but we've tried to list the versions which we've heard good things about, or have had positive feedback.

  • RB Twos
  • Garrett GTX3582R
  • Vargas Turbo Tech Stage 1 or Stage 2+
  • RB NextGen Plus
  • Pure Turbos PURE600

If you are prepared to use specialist fuels and fit an aftermarket ECU then the following are good options for those really big power hikes.

  • MMP1000
  • Vargas Turbo Tech GC 2.0
  • RB Super RB Evo 19T

BMW’s N55 Engine Tuning

The newer N55 engine was the successor to the N54. Similar to the previous version, it was also a straight-six turbocharged gasoline engine that was introduced by BMW in 2009 and is still in production.

The block and head of the N55 were also made up of Aluminum and thus the N55 was in many ways similar to the N54. The valve train was DOHC with VVT and VVL.

Differences Between N54 & N55

The N54 and N55 share many of the same characteristics but the most significant difference is that the N54 had twin turbos and the N55 used a single twin scroll turbo. Injectors are arguably better on the N54 but less reliable than on the N55.

Both engines had the same displacement and power outputs, but the N54 seemed quicker off the mark, the smaller twin turbos spool up more quickly than the twinscroll setup.

Spool up and power output was similar, with the twin scroll design spooling up making the car feel like a big NASP motor, a feature most drivers would want to retain.

Fuel Injector & Valvetronic

In addition to this, the fuel injector type was changed and Valvetronic was introduced in the newer engine.

Previously in the N54, piezo type fuel injectors were used whereas the N55 made use of solenoid type injectors.

The main advantage of shifting to the newer technology was that the outgoing injectors were more expensive although generally regarded as better, but slightly less reliable.

Advantages of Shifting To Valvetronic

The introduction of Valvetronic showed significant improvement in throttle response, exhaust emissions

The N55 was offered in the BMW 335i models after 2010.

Modifications & Tuning Options For The 335i

The N54 with its iconic twin turbocharger was a great vehicle however the car was electronically limited to a speed of 155 mph which provided new avenues of improvement to interested individuals.

Over the years several modifications have been performed on this great car however not all of them have generated the same great results.

Here are some of the modifications which when performed on your 335i are a sure-shot way of getting exceptional quality performance out of the vehicle.

Best 335i Tuning Upgrades

335i Limited Slip Differential

The eLSD on the BMW 335i was electronic traction control. Replacing the car’s differential is an effective way of increasing its performance and should be a part of any 335i tuning project.

Replace the stock differential with the limited slip differential (LSDs) which, unlike a conventional system, can vary the amount of torque sent to each wheel.

You must know the type of differential that came with your model to perform the required work, as BMW introduced the 335i with two different types: one with a bolted ring gear and the other with a welded ring gear.

335i Intake Manifold Port Injection Kit

For around $1849 you can get yourself the Intake Manifold Port Injection Kit from “Evolution of Speed” which includes:

  • Intake manifold with integrated fuel rails
  • Quick connect fittings
  • 6 fuel injectors
  • Fuel hose to fit into the existing fuel system

It can be helpful to address fuel starvation issues and can allow you to run alternative fuels and grades of fuel which have better knock resistance.

Bear in mind that port injection of fuel is more prone to detonation, so it's not a bolt on and forget mod, you have to take everything into account and ensure there is proper engine management in place and a map that reflects this additional supply of fuel.

335i Upgraded Spark Plugs

Using performance oriented spark plugs is a great way to increase the performance of the car as by using such high-end spark plugs, you will be able to burn all of the gas inside your car’s engine.

Most worn plugs we see are detrimental to the car's performance, and indeed a poor spark will show up when the car is tuned/remapped whereas on the stock maps you'll have got away with it.

Quality performance plugs also last longer than cheaper ones, so will maintain your performance for longer. It would be frustrated to carry out tuning mods on your 335i only to fail to fully realize the potential power they offer.

335i Spark Plug gaps & Electrode Options

Some N54 N55 owners have used a wider gap which makes for a longer spark, but too wide and the spark will be weaker so there is a balancing act to perform here.

Please note that multi electrode plugs are just a gimmick as you'll only get one spark and the spark is more shielded from the engines air fuel mix due to the extra electrodes!

Newer and improved spark plugs won’t increase the overall horsepower of the engine but will regain the power that the car was previously unable to utilize due to incomplete combustion. Another advantage of using these new spark plugs is that they prevent misfires.

The stock spark plugs offer adequate performance. However, newer and advanced spark plugs are a must for modified versions of the car that have added boost.

Why Use Colder Spark Plugs?

The use of colder spark plugs eliminates the problems that the OEM parts can’t. You can use the 1 step colder or the 2 step colder spark plugs for this purpose.

Cooler plugs transfer heat more efficiently so they help keep a lower cylinder temperature, and by reducing the risk of detonation or pre ignition you can make more power. However, keep in mind that these spark plugs need to be changed every 15000 miles.

Be aware that colder plugs will have carbon building up more quickly as the heat that would usually burn that away is reduced, hence the tip to replace them more frequently. A mid service schedule clean of the plugs is a good idea.

Ignition Coil upgrade options on the 335i

OEM coils are "pencil shaped" and won't support a high horse power engine very well, so an upgrade is definitely worth considering.

The coils were also prone to failure and are a potential weak spot so it's certainly worth getting these upgraded.

Every time you replace the spark plugs, don’t forget to replace the ignition coils as well. Companies that we recommend include:

  • Bosch
  • Eldor
  • NGK

335i Dual Cone Intakes & Induction kits

Dual Cone Intakes, also known as DCIs and induction kits or cone filters, allow more intake for the engine, resulting in more combustion, less restriction, and, as a result, increased power levels.

The DCIs serve as a supplement to the other mods you perform on your car but are effective as they produce immediate results.

They will not add power in their own right, they will just remove a restriction, and typically this will occur around 20% of a power hike.

The DCIs are also known for producing an impressive engine sound, which is a great feature that many people look for when modifying their vehicles.

Although the difference is insignificant, the DCIs also improve the fuel efficiency of the vehicle.

Expect your car's horsepower to increase by 20 after installing Dual Cone Intakes.

Go For K&N, or VRSF DCIs

One great option for your BMW 335i can be the cone intakes from K&N. Or you can also go for VRSF.

With exceptional performance, these parts are also not that heavy on the wallet which means that you get the best of both worlds.

Downpipes upgrades on the N54 N55 engines

The 335i stock downpipes with catalytic converters are often restrictive which means that they allow lesser air to leave. This affects the performance when a tuner is put into the car.

So with most 335i tuning projects this makes a lot of sense, as restrictions tend to sap your power gains.

Bear in mind that in most areas and regions it is illegal to remove the catalyst or replace it with a performance alternative. Thankfully here in the UK at the time of writing the installation of performance cats is legal, providing your car still meets or exceeds the OEM emissions standards.

Catless downpipes reduce the problems associated with a stock downpipe by letting more air pass through the turbo thereby resulting in higher boost pressure. Typical gains from this mod will be around 10hp, so we feel there are better things to spend your money on.

Adding downpipes is one of the best performance modifications that can go on a 335i before putting a tuner in it.

Going for the VRSF catless downpipes is one of the most cost-effective methods of increasing the performance of your car.

Warning: Removing catalysts is illegal in most areas!!

One point to keep in mind here is that by getting rid of the catalytic converter, your car won’t be able to pass the emissions tests. However, this is one of the most favorite modifications carried out by owners of BMW 335i presumably for off road use, or in regions where this is legal.

So some 335i tuning mods are not street legal. Beware of this and know there are perfectly legal alternatives around.

So why risk the confiscation or your car, or a citation, when there are performance alternatives around that perform just as well such as high flow downpipes and sports cats.

High Flow Exhaust Downpipes for the 335i

If you are concerned about passing the emissions tests, then instead of catalyst removal test pipes, decats or catless downpipes, you can check out the high flow downpipes on offer in your region or drop in to our forum and discuss your options in more detail.

These are better in performance than OEM ones but offer lesser performance than catless downpipes. However, your car is more likely to pass the emissions tests with the High Flow downpipes.

Remapping and tuning a 335i

If you are new to the field of tuning, let me first explain their types so you can choose the one that meets your requirements in the best manner.

There are two types of tuner options:

  • Piggybacks
  • Flash Tunes or Remaps

The biggest gains will always come from a bespoke tune/remap on a rolling road.

Piggybacks are plug and play devices that can instantly modify the performance of your 335i by installing the tune directly to the ECU. Piggybacks work by altering the signal sent to the car’s computer. They bolt in and can be easily removed so are favored by many.

The Flash Tunes are however different as they completely tune/remap the stock 335i ECU. Which is done with the help of the OBD port interface.

You can buy devices to transfer an ECU map to your car via the OBD port but we strongly recommend you get the car setup on a rolling road, where the individual nature and characteristics of your car can be taken into account and you can wring out every ounce of performance.

Piggyback Tuners & aftermarket ECU's for the 335i

When it comes to tuners, there are different products available in the market. Major products include:

  • Procede Rev3
  • Cobb Accessport
  • JB4
  • TDI Tuning - tested and reviewed on my Audi.

Boxes that come with multiple power settings and options are a good choice, as they allow you to set the power where you actually want it.

Depending upon the maps and the supporting mods you’ve done for your car, expect to see a horsepower increment of 60 to 80 hp with these tuners.

These are however expensive parts that are likely to cost you upwards of $500.

335i Intercooler Improvements

The intercooler or a Front Mount Intercooler to be more precise is a great way to get a significant performance increase. For more technical information see our article on performance intercoolers.

The purpose of an intercooler is to cool the air coming out of the turbo before it enters the engines.

Why is The Stock 335i Intercooler Not Good Enough?

The stock system of your car can perfectly function with low levels of boost and airflow but with the downpipes and DCIs installed, you will need an intercooler for sure.

If you put more heat into an intercooler, it will eventually warm up and it will be less effective at dissipating heat, this condition is known as heat soak.

So when tuning your 335i you'll be pushing everything harder, and heat soak is one frequent problem that crops up.

Infrequent high rpm driving rarely becomes an issue even after tuning, but if you do a lot of high engine speed driving then it becomes a consideration.

The stock intercoolers mostly fail to handle the boost pressures generated by tuners effectively. So, we suggest you replace the OEM part with VRSF 7.5" competition or race intercooler.

Another great option is the Masata 7.5” intercooler or the Masata Performance HD intercooler. Again intercoolers do not significantly add power, they remove a restriction and in some cases, this restriction has cost the car around 30hp.

Tuner Packages and Stage Upgrade kits for the 335i

If you are looking for great performance and don’t have much experience in the field, you should get a tuner package for your 335i.

335i tuning mods just got easier, when you find off the shelf packages that are tried and tested ways to make decent power gains.

They will have worked out the finer points and put together a package that works really well together. Plus if you hit on issues you are not chasing around multiple suppliers all pointing the blame at other parts.

The JB4 tuner 500 horsepower package is a great way to boost the overall horsepower of your vehicle across the 500 hp mark.

The complete package includes a large array of items including but not limited to:

  • JB4 Performance Tuner
  • JB4 Mobile Connect Kit
  • NGK 2 Step Colder with BMS Gapping Tool

335i Suspension Upgrades

Several suspension upgrade options are available in the market. Some of which are as follows:

Performance Suspension Bushes

The items available under this category include:

  • Rear trailing arm outer bush set
  • Rear upper arm outer bush set
  • Rear lower front arm inner bush
  • Rear lower lateral arm inner bush

When carrying out enhancements to the bushings here are things you need to know.

The suspension components of the 335i may be connected to the car's chassis through bushes, which are rotatable rubber mounts. These rubber ones will deteriorate over time.

Replacement OEM rubber bushes may have a major impact on the performance of your vehicle if your existing ones are worn. Worn bushes may also accelerate the decay of other suspension components due to the increased vibration and play.

Poly Bushes

It's probable that the ride may be a touch rougher because of fitting stronger polyurethane bushings but they'll last longer and maintain tighter handling.

A new set of poly bushes may be able to minimize the excessive play that comes with rubber bushes.

Some polyeyurothane bushings are hard to locate, but most will find the primary mounts readily available in their areas Often, custom 335i poly bushes may be manufactured to your requirements.

335i Strut Braces

Wiechers racing line aluminum/ carbon look strut braces are available for all E9x models including the 335i. A strut brace will keep the suspension alignment in place, and is something I regard as essential on older higher mileage cars.

335i Air Ride Suspension Kits

Although several options exist, here are two examples of good ones:

  • Air Lift Performance 3P Digital Air Management
  • Universal Air Lift Performance 3H Kit

See what we think of this upgrade in our air suspension guide (it's not really a performance mod).

335i  Lowering Springs

Do you want to lower your car and are looking for effective lowering springs? Try one of the following to get the best results:

  • AC Schnitzer lowering spring kit;
  • Eibach pro kit springs;
  • H&R lowering springs;
  • KW HAS height adjustable spring kit;
  • KW lowering sprint kit.

Complete 335i Suspension Kits

You can also go for the complete suspension kits from one of the following brands which promise exceptional performance:

  • AC Schnitzer racing suspension
  • KW Variant 3 Coilover kit with and without EDC
  • H&R monotube Coilover kit
  • BC racing Coilover BR Series
  • Eibach Pro Street S Coilover

Cosmetic Modifications on the 335i

There are several cosmetic modification options available in the market for the BMW 335i. As the vehicle belonged to the E9x series, all cosmetic modifications of the series perfectly fit this car as well.

See our E90 E91 guide for more information on this aspect of tuning, just so we don't have to repeat ourselves here, and I'm sure you only came to this site for performance mods.

335i Alloy Wheel Upgrades

In addition to delivering extremely good performance, a modified car also needs to look good to complement the performance.

A car’s wheels play a significant role in upbringing its looks and with the BMW 335i available in 18 to 20-inch wheel options, you have a lot of choices.

However, it is pertinent to mention here that with the increase in wheel size, even if you install low-profile tires, the performance takes a hit. The car’s suspension and brakes are also affected by using bigger wheels.

The ride quality deteriorates when you switch to larger wheels but research shows that shifting from 17 to 18” has little effect on performance and ride quality. However, as you move on, the effects become more obvious.

There will be a lot of debate here, but we would insist on 18"s and no larger, unless I was doing a track day, when a set of 19"s with road legal slicks would be my choice totally for it's performance advantage.

There is also the additional cost of the tires, and the risk of kerb damage to your rims, so the smaller rim sizes have a lot to recommend them.

If you would like to know more, or just get some friendly advice on Tuning your BMW engine please join us in our friendly forum where you can discuss 335i tuning options in more detail with our N54 owners. It would also be worth reading our unbiased BMW tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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One Response to “335i Tuning”

  1. Richard Harris says:

    I have a 2007 BMW 335i sedan. I am restoring it and trying to keep it running well. I have already spent over 3500.00 on new parts and repairs. I am having passenger side heating problems currently. I like the car and want to continue improving it. Your articles are informative and interesting. Do you know if plug in horsepower boosters actually work?

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