91 octane on DOT slicks. i had to drive the car back from denver 80+ miles when a hub went out on my trailer and it never gave me a problem. it will not over heat sitting in traffic but i would not want to push it too long at a stand still being it is aircooled. it likes to be kept over 3000rpm for the fan to cool the motor.

as for close to stock :P
its a dune buggy weighing in at 1450lb with a 2110, turbo charged currently running 12psi, and a custom mapped GM EFI system. it dynoed 149rwhp and 152lbs of torque uncorrected