Frank is right. Lowest octane w/o pinging is the way to go for power. Race gas is at the track because at the track there are cars with 12:1 compression and 30psi+ boost pressures. These types of motors can NOT run on pump gas due to pinging/detonation and if they do it will send the motor into shrapnel. There is a thread on here about gasoline/octane ratings. However, I run 93 for piece of mind since we do not have knock sensors or any safety measures for detonation and I consider our engines high performance, pretty high compression and high revving. I would just hate to see what would happen to an engine detonating every cycle at 15,000rpms. I know I dont want my leg near the motor is all.