I have the WS2 and am very pleased with it. I think I gained a whole whopping 3hp. but big gains from an exhaust are to be seen on boosted cars over N/A. Your choices should be RSR ExMag or WS2? Cause your choices now are chambered ws2 vs. straight through EVO2. Do you want to be loud or quiet? Make that decision 1st and then go from there.