I usually fill my tank with 91 benzine in Pai before I ride to Chiang Mai. Today, I had to make a quick dash to CM and back and didn't fill up before I left. I went to the service station in CM near Makro on 107 where I usually fill the truck on trips to the big smoke. Riding back it was as if the bike was supercharged. The difference was remarkable. The pick up both from the lights and rolling was simply astounding. I always buy 91 benzine and have never put anything else in the tank. Something fishy is going on!