Just got done installing these babies on my stock h-pipe and I'm actually quite impressed. They weren't as loud as I was predicting (I assume because of the stock piping), but one thing I wasn't expecting was the increase in throttle response and high end acceleration. As soon as I pulled it off the pit, I got on the road and laid into first gear and the car put me in my seat... Something it wasn't capable of doing before as the engine is completely un-modified aside from a K&N air filter. So I continued driving it around and let it warm up to normal operating temperatures and it still moved just as quick. Figured it was maybe just in my head, so I let my buddy drive it as well, and he also said it felt alot more responsive. Anybody else had experience with these mufflers giving a noticeable performance increase? But anyway, back to the main point, I'd recommend these mufflers to anyone looking for something that isn't too high pitch as they are alot deeper than the standard 40's, but still have that 40 series growl around 2,000 - 2,500 RPM and at idle.