greddy: I don't know about the power it makes, but it sounds awesome. The tip is way too huge, though. Cut it off and weld on a smaller one. Anyways, I've heard that the EJ25 doesn't respond very well to muffler mods. I haven't heard what the others sound like, but the greddy on my car (combined with the borla headers) is really deep and rumbling. I like it a lot. Now I just need to add a turbo, so my car will have enough power to back up that mean-sounding exhaust note.