I have been running around for a few days now with the Gruppe M intake on my car. It is the only mod done thus far. Well the intake isn't really mine per say... but I might just keep it. Anyway the intake noise has increased a bit as expected. I can only really hear things with the windows down though. I would like to test out downpipes in combination with the intake next and also in combination with the stock intake.
I have never really encountered so many people who weight their modifications according to price versus amount of horsepower gain. I guess I have just been brought up in a much different area of the performance world. Personally I look at price according to quality of manufacturing and ability to perform the intended function.
The product in question here in an air intake. You can't expect more of it than any other product of the same function. There is no comparing air intakes to exhausts or ecu piggy backs. They all have different intended functions. You either want an intake or you don't want an intake.
Since interpolating the numbers on a dyno sheet can be annoying here are the exact gains at a few RPM points:
The Gruppe M intake provided about a 6% hp gain. Anyone who might desire to achieve above a 10% gain with an air intake is a bit naive. The only car I have been able to gain a substantial amount of power (10%+) with only an air intake is the '05.5+ VW Jetta. If you have seen the stock intake system on that car is it extremely restrictive with many varying cross sectional areas (the intake runs through the engine cover...)