OK, I know these are probably stupid simple questions but I need some help. I purchased a Q4 muffler off of sleezebay last week and it came in the post today. I was told ahead of time that the muffler didn't have the quiet insert or a spark arrestor so I ordered a replacement part from RMATV. Tonight I unwrapped the pkg (original packing with correct part # for FMF Q4 for 2004 CFR 250X) and mounted it up on the bike. It fit the bolt holes with no issues however I seem to have some minor trivial problems so I'm pleading out for some knowledge: Muffler mounted on the bike with stock X header/mid pipe. Replacement FMF spark arrestor/quiet insert for the Q4: First Problem: #1.) The Muffler pipe is a larger diameter than the stock mid-pipe by about 1/4-3/8". Can I just use high temp silicone tape to close the gap? Should I get a replacement stock mid-pipe gasket however doing this will close the partially but not 100%. Also, because the FMF pipe is larger than the stock muffler pipe I am not able to reuse the stock mid-pipe clamp. Does FMF make a clamp for this or what am I suppose to do here to clamp the exhaust to the stock mid-pipe/header? Second Problem: #2.) For the sake of typing it out, when I refer to the "spark arrestor" I'm referring to the combo FMF part which is a spark arrestor & quiet insert (1-pc). Installing the new spark arrestor in the end of the muffler (in the cone section) is a super tight fit. I cannot push it completely in by hand. In fact to get it in (I think this might work) I'd have to spray it with some high temp silicone spray and then I could probably tap it in with a mallot or something however I know I'd never be able to get it out again if I had to. Anyone else ever replaced the insert? How did it fit? Issues? W/O Insert installed: Looking down inside of the muffler: Trying to fit the insert/spark arrestor (tight fit!!) Recommendations: #3) Would anyone recommend replacing the stock header/mid pipe with a FMF part? If so, which one? I would hate to lose bottom end power. #4) Rejetting: I have the air box mod and o-ring mod already done. Running #40/135 jets and the clip is currently in the #4 position. I'm at sea-level. Do I need to rejet? If so, to what?