I just put the exhaust on today and can't be happier with it. Yoshi is claiming about 7-8hp gains through out the power band. I know Sparks is claiming about 10 hp, but who really knows????? What I can tell you is that the Yoshi sounds awesome, will meet the impending 96db requirement for 2004, looks very trick, was the easiest exhaust I've ever put on anything, and weights a whooping 3.8 lbs - which is about a 10 lbs weight savings over the 14 lbs stock system. In the end, I don't think anyone can say they have the "best" system period, but I don't think anyone would argue that the Yoshi system is a very good kit - argueably one of the best. Is it worth the $$$$$ they are asking for it, I dunno, a friend works for Yoshi so I got the killer discount, about 60% off - it was very worth it for me!