I was just wondering the octane needed for the dome sizes from 17cc up to 22cc from Pro Design Domes. I have 20cc now and sometimes mix race gas 50/50. But I want to be able to use just pump gas 93 in a pinch. Banshee is 2002 with Cool Heads, 0.30 over with Weisco Pistons, Tors Eliminator Kit, K&N Air filters fight off carbs, +4 timing, rebuilt carbs, 300 main jet with 30 pilot.... Also with these minor mods I want to beef up the power alittle more.. Besides porting and welding and balancing crank what else are somewhat inexpensive ways to gain hp. Any info will help..