I currently have an FIPK on my AP1 and the sound is incredible. I like it because it's essentially stock noise levels at low throttle openings, but growls nicely when you open it up.

Ultimately I will likely end up with a kraftwerkes kit. Crazy as sounds, however, my second biggest reservation (after increasing complexity/number or parts/potential for issues) is giving up the sound of the FIPK.

Obviously I've watched youtube videos, but have never heard a rotrex s2k in person. Can someone who has heard both please comment on the difference in sound?

 

Its like a K&N .... at idle you hear a faint whine from the SC ... and when you go WOT you will not be thinking about intake sounds anymore

J