As expected the noise output is definitely toned down compared to the older Q4, especially at running and sound testing RPMs. You can really hear the difference yet the muffler still allows a good sound, especially to the rider where the crack of the throttle or the snapping noise is pronounced. On the bike you hear a snap but to someone off the bike it is not noticeable. And compared to a Powercore 4 the Q is definitely much quieter. The good thing is that the power is minimally affected, especially considering the reduction in sound. The unit we were riding with (on three different bikes, 2012 500 EXC, 2012 350 EXC and 2008 530 EXC) didn’t lose any throttle response or snap compared to stock or the older Q and in fact seemed to pick up a little there. Then the muffler promotes a very linear or progressive build of power and the FMF guys think they could get even more out of it here with minor tuning, hence why we were riding it. Funny thing was that it really picked up on the carbureted bike compared to the FI machines, typically jetting is required when a restrictive or quieter muffler is installed so this thing must flow.