I just installed a Q muffler and Power Bomb SX head pipe on my 02 426. I removed a White Bros e muffler with all discs installed and stock head pipe. I have to say I'm disappointed with how loud it is. I haven't had it tested but to my ear, it's pretty close to the worn out e. I'll be surprised if it's under 96 dB. Performance wise, with the carb set up for the e, I had a lot of popping and it ran pretty crappy which implies it flows better than the e. Richened up the fuel mix and It runs a lot smoother and there's a noticable power gain, especially low and mid (as advertized) even though it was no slouch with the e. Would I buy it again? Not if quiet was my # 1 concern (which it was).