Essentially, nearly all 1.8T engines are the same. The TT's main difference for the added power is a KKK K04 turbo where as the 150bhp models use a KKK K03 turbo. There is a Haynes manual about the Audi TTs development history which lists all the differences.
You can get a better, quicker spooling turbo from the Garrett GT series to bolt-on to your engine, but you should consider uprating all your brakes, clutch, suspension, air induction and heat dissipating components first.
The ECU (Audi will say its not the same) but in hardware terms it is, it just has a different software program written for it which controls the engine timing, boost pressures, fuel pump etc.
You can change the software in an A3 courtesy of dealers for
www.revotechnik.com or
www.custom-code.co.uk and quite a few others. They can in some cases give you multiple software programs which are switchable between standard, hi-octane fuel, race fuel etc... all of which adjust your engine timing, boost pressurs and what not to give you much more BHP. For £400 notes, a remap of the ECU is probably the best mod going on any car from the Volkswagen Audi Group. The reason a remap can give you more power is that a 1.8T actually knocks out more power and the cars are essentially dumbed down by the ECU program to be less sporty, cheaper, more economical and cheaper to insure. A remap will unleash a lot more power and most importantly torque, allowing much quicker acceleration.
If you are wondering if you could toast a TT 225, then with A LOT of expense the answer is yes. If you bought an older A3 recently, say 2000-reg, then for a few grand (£5k-£7k) on top, you could have something which leaves most cars looking limp. If yours is FWD and not Quattro, then on a track you wont be able to keep the speed up in the corners and you'll get beaten, but on a straight, if you can control the torque steer and are good enough at ensuring you are not spinning the wheels, then you can get seriously good results.
A good example of cheap supercar power is the modded cars the police sometimes use (unmarked ones). There are two that patrol the M3 in Hampshire, both Skoda Octavia VRSs and so had 225bhp to start with. They have a Garrett GT2871RS turbo swapped out with uprated fuel injection, fuel pump, clutch, exhaust system and brakes. They are then taken to
www.custom-code.co.uk and given a custom remap to make use of the power. The finished car is a normal looking VRS with 450+bhp because custom code do a little secret extra work on them to get more power. These Skodas will do 0-60 in a little over 4 seconds. If you are wondering, the Silver unmakred is license plate is CX54BAO and the black one is OE05FKJ. Two days ago I saw the silver one pull over a white Nissan Skyline R32 GTR. If you are going to have a fast car, it helps to know the unmarked police vehicles in your area
* VAGrant *