My wife runs the fmf-q muffler and power bomb header on her 440 and it performs very well and it is holding up as good as any other pipe that we have owned.

 

I have had the power bomb header and q muffler on my 400ex for about a year and a half now and I really like it. When just cruising around its real quiet but when you "get on it", it has a pretty loud bark. The only issue I have had so far is the fact it is a little long.

 

The muffler is fairly loud!! My only regret is that I am afraid I will eventually have to run the "quiet core", because there is a 96dB law on public land here in Calif. It might however, improve low end power (like a torque stuffer), so the tradeoff might not be all bad???

 

I run the Power core IV with Power bomb header on my 440. I installed them two years ago before the 440 kit and got a nice performance boost. More than I was expecting and since have had no problems at all