I bought my 2009 WR450 used and it was already fully uncorked and has FMF Factory 4.1 Titanium with power bomb header. I just repacked it and no leaks. I am not happy with how loud the bike is and the popping on decel. I am considering a different muffler and possibly the FMF Q4 Ti. Can anyone tell me how much the Q4 will quiet the bike down and what else to expect over the 4.1? Thanks!