I did the 1 part / 2 part mix using what I could find. Traxxas Top Fuel 10% and gas. If compression ratio is my problem then that is easy enough to fix. I would have to special order the S T fuel or drive 120 miles round trip to find it in Sacramento. My local hobby shop just closed in December. If I just don't get in a hurry then I can get S T fuel next month when I have to go through Sac. on my way to Reno if I-80 is clear.