I saw somebody else had this same thing a while back I think. My car pops out a small backfire quite often when shifting at partial throttle (not to mention it's hard to start) since I installed the 450cc's and removed the FMU. Had anybody with an SOHC revised their AFC settings and found a better way to go than what was mentioned on the AFC hack page? I'm sure once I get it on a dyno I can get it worked out but the pops are annoying.