I have no experience with FMF 4-stroke exhaust, but I did have a CT/FMF hybrid pipe on my blaster and it had a good quality craftsmanship, and added power for sure. As for the price it can't be too much, the install is pretty easy, just make sure you spray a little WD-40 on the exhaust stud nuts/bolts and let soak for about 10mins. before removal, also if you do get the exhaust make sure you rub it down with some regular rubbing alcohol to remove all the oily fingerprints prior to start up. My friend has a 1998 TRX300 4X4, and man he put a UNI filter, DMC Alien slip-on and a dynojet jet kit, and that thing moves for a 300 with 27" Vamps. He raced, and I witnessed it, a 2005 Rancher 400 w/27" 589's and my friends bike won by atleast 3-4 bike-lengths. I would say DO IT!!!!
thanks im running 27 mudlites and a lift kit imma get it for my b-day hopefully