I, too, felt better throttle response w/ my K&N. Really, though, it's not the airbox that's restrictive, it's the filter size. KKM has SO much more filter area. That's why it makes more power than the K&N. Unless there's heat soak...
xselseeor - btw, welcome. what's your name mean?? Here's my advise - everyone who owns a KKM setup likes it (so I hear). you'll feel a difference in power, and you dont NEED to free up the exhaust, but I warn you, mods are addictive
