Short RAM intake vs Cold Air Intake?


New member
Edmonton, Canada
Alrighty, here's the scoop,

I think I've kind of figured out where to start with my Mazda3. I was getting my oil changed at the dealership and was flipping through the parts guide they had displayed at the counter.

I found some relatively inexpensive mods I can start with to add some cheap horsepower. The first is a Cat Back exhaust kit to increase the air flow out of the exhaust. The description said it would add about 10% extra horsepower. I still have a lot to learn about the tuning and mod world so I did some extra research and from what I understand the Cat Back kit basically replaces the exhaust from the Catalytic converter to the tail pipe with a larger diameter pipe that is mandrel bent so the bent pipe isn't crimped from the bending machine. This is supposed to increase air flow making it more efficient so the engine doesn't have to work as hard to expel the exhaust. It also makes the car sound a little throatier which is plus for me as well. :bigsmile:

The next two items that caught my eye were a short RAM intake and a cold air intake. The the short RAM intake keeps the intake inside the engine compartment but it's shorter than the stock intake (not sure how that is supposed to increase horsepower). The cold air intake made more sense to me as the intake is positioned outside the engine compartment letting the engine breathe cooler air which has a higher concentration of oxygen. This is where I could use some help in making a decision. The cold air intake helps produce more power but as the intake is positioned outside the engine compartment toward the bottom of the vehicle, if you run over a water puddle the intake could get wet and cause hydrolock which can destroy the engine. The shorter intake doesn't have this problem but the increase in power isn't as much.

between the Cat Back kit and the cold air intake I would get about an additional 20% horsepower turning my 167 hp 2.5L engine to a 200 hp engine.

Has anyone applied any of these to their vehicles? Is my understanding correct on this? Am I going in the right direction do you think?

Any feedback would be helpful and much appreciated:bigsmile:

Yea those are the mods that people usually start off with when tuning. Exhausts and intake. If you're going for a little bit more power, then I would suggest the cat-bat over an axle-back exhaust. Axleback is little to nun power gans and they're mostly just for the sound, unless you want to add a mid-pipe, thus making it a full cat-back, if I'm not mistaken.

And as for the intake, I would say go with the CAI (cold air intake). Unless you live in a place where it rains like a b**** every so often, then you should be fine. And also there are things called "Hydro Shields" that you can put over your filter so you don't get water in it if you go in a puddle. Now I'm not sure if they totally block ALL water from entering the filter, but they block out most of it and some dirt particles as well, and that's a pretty good deal considering that most people I know with CAI don't have one and are doing fine. Just avoid big puddles or go really slow through them and you should be good.

And I'm not sure if a cat-back and intake would increase you to 200hp. Companies tend to just say that their products will increase you "x" amount of hp or "blah" amount of hp. But after you've driven on the road for a while, you're car tends to "lose" the hp it came with stock. Like from the driving you've done with your car you probably have about 160 hp or so, if I'm not mistaken. But I might be wrong so bear with me. In reality, no intake will increase your car's horsepower more than say 15? at max hp. And that's a lot for an intake. Maybe if you get the right products you might be close to gaining 30 hp with a cat-back and intake.

If you're looking for a little boost of power but not yet ready to go F/I or anything major, then yes you're going in the right direction with a full exhaust and intake. As I said most people start off with these mods as their first, because they're easy to install and give a short but slightly noticeable boost of power....

Have fun!
Hello and welcome to the site mate

ok cat back wont add that much as the most restrictive part of the exhaust is the cat itself. even removing this or fitting a sports cat doesnt actually add 10% power without changing fueling.

cat back if your lucky will give you around 5-10 bhp if your lucky with it being alarger engine

the short ram intakes work better by having a larger filter size, depending on the filter fitted as some are actually a smaller area, and lower restriction. so more air can enter the engine.
CAI work on the same principle but take in the colder air away from the engine. as youve found out your self the hydro lock issue causes worry but you ether need a deep puddle or a long pipe before your really worrying as long as your sensible.

best bet id go with is short air with a cold air feed directed at it. this way if you do run through water the effort required to suck the water up the pipe is less than that of sucking the warmer air from around the engine so water shouldnt be sucked into the engine.

both filter and exhaust id say gary's guess of 15bhp sounds about right.

for my example a cat back and enclosed CAI i gained a whopping 8bhp on a 1.8 turbo
Cool. Thanks for the info guys, I appreciate it. This has actually peaked my curiosity a little now. What kind of intake do Rally cars use? They run in some pretty dirty and wet environments so if they (I am assuming as much) use a CAI what do they do to protect from hydrolock? Do they use a hydro shield like Gary had mentioned or a cold air feed like pgarner had mentioned. Jarrus had mentioned doing a remap to exploit the added air flow from changing up my intake and exhaust. Am I correct in saying that that is basically tinkering with the car's computer? Sorry for all the questions, I know they're quite basic but I'm learning a lot here.
To be honest, I'm not sure what rally cars use, it depends on there setup I suppose. The NA rally cars use an ITB arrange ment (individual throttle bodies) so would use a carbon air box of some kind and a filter in a box.

I tend to find that the best kits are ones you've made yourself from larger engined cars with massive airboxs like the Vauxhall VXR8 (think it's a pontiac gto on that side of the pond) then you can't go far wrong with that.
To an extent.....yes I really high-powered applications then it becomes more important.
Forcing the same volume past a restriction in the induction system, thus running a high pressure means higher risk of detonation, and means ultimately making less power

But in a road car I suppose it doesnt matter
I was watching some of the WRC a couple of weeks ago, forget what country. But they said the driver and navigator can operate a mechanism, that, if I remember correctly, blocked the primary intake opening and let air bypass at some other location.

Personally, I would go with a CAI. Also, a K+N intake is likely cheaper and less restrictive than whatever the dealer has to offer. However, if you're worried about water, I would just get a K+N air filter. It might only give 2-3hp more, but you won't have to worry about water and you'll save money since the K+N is reuseable.
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I just use plain old pleated paper filters from the dealer. Replace them when they start to look a little dusty. At about a fiver each it's not worth the hassle of cleaning and oiling etc. But I'm also not bothered about another 2-3bhp.
Wrc engine bay.
Hey guys,

Ok I think I've decided on a CAI as opposed to the short ram intake. The HP gains are a bit more. As far as brand names go I have a choice between AEM, Ingen (I think that's how it's spelled) and Takeda. I can't find anything from Ingen that fits my 2.5L Mazda3 only the 2.3L supercharged MazdaSpeed3. Surly they also make one for my 2.5L?...right? Haha. The Takeda advertises a few my HP gains than the AEM and it also comes with a hydro-shield. Don't know much about either brand and was wondering if I could get a general consensus as to which is a better buy. Price wise they're pretty much the same.

I've also decided to go with a Magnaflow Cat-Back exhaust. I found that going outside of the dealership saves me quite a bit of money. Wish me luck.

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