Originally Posted by chops

there is definitely rasp if you had test pipes (resonated or not) or high flow cats to the nismo exhaust. i believe the H pipe is the culprit here. the new cats/tp's go from 2.5" pipe to the 2" flex pipe flanges, which open upto 2.25" to the midpipe/resonators.

a member in the nismo forum said he added a custom 2.5" x-pipe which got rid of all his rasp. im determined to go this route as well...as soon as someone makes one!