I just bought a 2008 kfx last week from a guy who knew NOTHING about it and he didn't ever ride it (that's why he was selling it) he bought it from the original owner 6 months ago. Anyways he said the thing was bone stock besides the front bumper, I looked it over very well but still failed to see the different FMF header when I met the guy (he was still running the stock slip on so I didn't even think about it.) Paid $3,000 for it and brought it home to find the FMF header and lifted up the seat to find a PC3 and an open air box lid along with no spark arrester. I was shocked. Runs great and idles a little high but anyways I live in a residential area and my neighbors don't like me the way it is and I was thinking about putting in a spark arrester to dampen the sound a little bit and was wondering if I would have to re tune/map the PC3 if I did install a spark arrester. New to this forum thing so please forgive me and any tips would be appreciated, thanks!