Ok well here's my report. Got my FMF Powercore in the mail on Thursday. Went riding this weekend and I must say I was very impressed with the power increase on my 2004 WR450. I'm currently running it without any insert in the baffle and it's just slightly louder than my stock exhaust with the baffle removed. I really don't think it's all that loud at all. Awesome pipe, really good mid and top end power. Low end is so-so but still love the new TI Powercore and highly recomend it to anyone. Can now pull wheelies in 4th gear with not much effort. I put 120 miles of desert riding on my WR with this new pipe and it runs great.