I've run av 100 low lead for a couple of seasons in my 200exc with no problems. I notice just a tad less tendency to stall at low rpm's. I didnt notice much difference on the idle, but I tune mine to not stall while idling in gear with the clutch in. It will not ping, even flat out in 6th (long straight across a pasture at the last race high humidity and about 93degrees). I figure it doesnt cost that much more than reg gas and if it stops detonation, then its worth it. My 200 has never fouled a plug, and if its over 75 degrees, needs no choke, and starts 1st kick. I'll keep using it as long as it stays resonable. Good luck with your GG'