I have Br9es plugs in my banshee. I run 93 octane gas. The guy at the autoparts said thats what hisbook called for.I seen another post on here where it said these plugs were for alcohol. The banshee is banging and backfiring now when I punch the throttle. It didnt do it the first couple minutes when i first put the plugs in but it is now. May be running a little lean also but it has been running alright. Plugs dont look bad. I put a throttle cable on and changed plugs at same time. Running 280 main jets at 550ft elevation. Have fmfpipes, unifilter, and a milled head to 21cc. Also what crank case oil do yall run?