When I changed my frontpipe with a catted/custom resonated Berk frontpipe (Tomei headers+overpipe already in the car, stock catback) the only difference was cleaner boxer sound than with the factory frontpipe and slightly louder.
So it really depends from the frontpipe resonators, buy one that has at least two of them say Apexi, HKS etc, I sell mine almost new but you are faraway!
