M2s I went with the 40 series flowmaster and love it ,,, It's loud at frist but sounds like a V8 .. A deep rumble... I at the same time did the pipe back and was surprised to see the stock bend in the pipe that went over the axle ... the 2" pipe was comprest to 1" and then back to 2" ... the shop did it right and went 2.5" .And wow what a big improment. The cats are next.