I have had the K+N filter fitted and the induction noise and a slight increase in reponse is there. There is acouple of other low cost things you can also do.a)Use optimax fuel b)Fit a straight through induction pipe(replaces the air baffle box after the air filter) for more induction noise.c) Fit a sports exhaust back box(if not already done). As the K + N filters don't need cleaning until 40,000 miles use, the job is not that often done.