I had the Aeroturbine 4040, it has the built in resonater, cost me $250, it was really loud, it is much smaller than the stock muffler, had a nice deep rumble at low rpms, but it finally got to me and I wanted some peace and quiet. I cut it off last thursday and welded in a Rokktech, now I can hear my stereo without having to crank it up, and it is a straight through pipe, so no restriction, I am very happy with the Rokktech, it only cost $150. The Aeroturbine is stainless and polished and the Rokktech is just spray painted alumnized steel, but I can't see it from the drivers seat. If anyone is interested I would sell the Aeroturbine, its not too big so you could get it to fit in tandem with your existing muffler, Aeroturbine claims thier design is better than straight pipe because it actually accelerates the gases as they pass through. The only thing is the Rokktech is huge and will be the first thing to get slammed by rocks if I go offroading, but I am loving the sound and with the silencer ring MIA I can hear the turbo whistlin real nice.