I really like the sound that a blow-off valve makes when they are in audi tts. So I was wondering if I got one for my '02 225hp Audi tt if it would damage the engine in any way. I have read that diverter valves are better, but I want the sound of the blow-off valve. Also any recommendations on blow-off/diverter valves would be great.
Well, in the audi system it expects to get the extra boost back from the diverter valve so it would be against your best interest to blow off all the boost. However, they do make blow off valves that sound great but only lose 10-30% of the boost which would have little to no effect on the car and you still get that cool sound. I personally am not into blow off valves so I've never bought one but I've heard some good things about Forge blow off valves and I believe they make a 30% blow off like what you would want.
Blow off valves are nice, but they aren't terribly good for your car. The main problem is that when the turbo isn't running, that open valve will suck unfiltered air into the engine and can seriously damage it. Blow offs are also pretty inefficient as you lose a good portion of the air in your turbo system. The best thing you can do is just get a good Forge diverter valve. Well made, looks nice, and will add a pretty decent amount of performance.
