Open air filters really are "fun"... why? cuz they make u wanna rev the hell out of your car to feel the induction noise and it does make your car "noiser"...
Having that said, let me tell u of an experience that a couple of us had... We were lucky to borrow a Scantool that we plugged into the "test" cars:
1. 2.0L 320 sedan (Blitz)
2. 2.2L 320 sedan (GruppeM)
3. 2.5L 325 coupe (Blitz)
Result? All same! :shock: The amt of air entering the engine etc were about the same! But the induction noise of the GruppeM is definitely louder than the Blitz, partly due to the "trumpet" design of the intake!
Just food for thought yah? Cheers!