Power Extreme PE-R™ 304 SS Cat-Back Exhaust System with Quad Rear Exit by GReddy®. Exhaust Type: Cat-Back. Exhaust Tubing Material: 304 SS. Main Tubing Diameter: 3.5" to 2.36". Exhaust System Sound: Aggressive / Loud. Today’s sophisticated tuners want it all, and GReddy’s SE exhaust systems deliver the full spectrum of features desired in a street performance system. SE exhausts increase flow via tuned piping and larger, free-flowing mufflers for improved power, but provide discreet sound levels that won’t attract the wrong kind of attention. The exhaust note is comfortable and sporty, not loud. Each application is tested and tuned for USA spec. vehicles, so fitment and sound is confirmed.