Originally Posted by stefan
Not sure what you mean by this, but you can't replace induction noise with exhaust noise. Try revmatch downshifting in a 335 and you'll see what I mean.
I assumed you were talking about the exhaust noise, when I made that post. I see you were talking about induction noise.
Seeing as I have an N54 and I rev match on downshifts all the time, I know exactly what you mean. The only time I've really enjoyed the induction noise my car has made was when the charge pipe would separate from the intercooler outlet. Man, I was tempted to just leave it, because the car sounded so much better.
I think that induction noise could be significantly improved with a shorter intake and a paper-cone filter. Forget the airbox, just stick the filter on the impeller housing.
Editl: BTW, your car is gorgeous.