Nothing other than sound. Raspy on cold start up. I'd go with an aftermarket res. like a Magnaflow. i.e. bullet muffler.

-'96 SE MTX 3L -'98 SVT 1,173 of 6,535 -'05 Mazda 6s, loaded, g/f's ride -Need a 96-00 manual on CD? PM or email me