I am in the process of increasing horsepower with more boost in my turbo. What's the max boost I can do if I did the k&n air filter upgrade and put a 2.5 down pipe and 2.5 inch exhaust all the way back?

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    Firstly I would ask have you considered the ECU in your plans? In the 2.0 TFSI the ECU "requests" boost from the N75 valve. If it sees anything outside of the range it expects you'll be generating faults in the ECU. Commented May 27, 2016 at 5:21
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    What mechanism are you using to increase boost? What engine code do you have? Commented May 27, 2016 at 5:25
  • @StevenRichardOakes You have a very very good point there.
    – Shobin P
    Commented May 27, 2016 at 11:08

2 Answers 2


It just so happens I wrote a How-To article on AudiWorld.com about tune reviews for the A4 B7 platform.

For instance, you can purchase a Stage 3 remap of your computer from GIAC (assuming a 2.0 TFSI engine) and have the car produce an extra 100-130hp with 75-145 lb-ft gained in torque. Not only will you want your cold air intake, but you'll need some other mods as well (read their page). For a 2.0 liter engine, that is some serious power gains. The engine itself stays stock. The mods they talk about are all supporting, to ensure your engine is compatible with the remap of your computer. You can purchase their Stage 1 remap, which will give you an extra 30-60hp ... which is still a serious kick in the pants.

Bench racing your engine (ie: How much will my engine make if I ...) is not anywhere close to an exact science. One of the reasons is, I can tell you to throw a tank of nitrous onto your car, let you blow as much laughing gas into the intake as you want, and the engine will produce 1000+hp ... the real question to ask here is: How long is my engine going to last? ... the answer to that question is: Not very long. Consider that when combining to make horsepower in any situation.


You can boost away almost indefinitely until the AFR goes lean or you start pre-detinating (knock).

At which point you'll need a new engine.

But once you get outside your turbo's compressor efficiency map, more heat, less VE, and a whole bunch of other concerns. Time for a bigger turbo.

Are you going to run 93 pump, E85, meth/water spray?

First post is spot-on; you need a good ECU tune (and great tuner) to realize any benefits from bolt-on mods. Otherwise any power you perceive gained will just be a result of leaning out your AFRs, and eventually causing stress and damage.

Just changing the CAI is likely to need a MAF remap. Otherwise, lean and possibly boom!

It's an expensive slippery slope (but fun). Just ask me-I can barely afford to type.

Please, please, please get a proper ECU flash.

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