As Kahbrohn is wondering, is there in increase in low end power and acceleration?
I've READ while researching, as any mindful person would do before altering a vehicle, that aftermarket/performance exhuasts may increase mid-hihgh range power, but might decrease low-end power. Has to do with the loss of back pressure, and this may not be noticable on hihg-power engines.
For our I4 I'm afraid I'll lose low-end power/torque, which I prefer to keep so it's there to get me up steep inclines and out of mud on my occasional adventures. As far as volume, I think we';ll hear the engine and exhaust pretty much all the time anyhow, so why not make it sound good.
After catching Earthworm's short clip of his mod'ed 'Riot, and comparing it to a couple other videos on youtube, I am starting to lean more in favor of the Flowmaster Hushpower. Problem is, so many people put the darn camera right up the tailpipe and the microphones on most camera's pick up all the air noise insted of the exhaust note...