I was wondering if someone would be able to help me with a problem Im having with my WR400. The bike had an FMF powerbomb header w/stock pipe and some sort of baffle at the end of the pipe. (Ive attached a pic with the original set up) I replaced the silencer with an FMF Titanium. Ever since I change the pipe the bike backfires or pops alot when I let of the throttle. It seems to run nicely until like I said I let of the throttle. Any suggestions? Im afraid its going to do harm to the engine. Also the pipe is load as hell. Is there any way to quite it down a bit?