Yeah apparently AMA and a ton of ppl don't like us fixing rockets to our airplanes, i built an electric switch that was activated off of my gear channel to fire a rocket, not for boost, but anyways the whippits are what i used. To puncture the top i used a thing for pumping up hockey skates with CO2 and it worked fine, i cut the adaptor thing off the top and plumbed in a 1/4 feed line. The main things that i think you'd need to make out of steel instead of aluminum, or make beefier ones, would be the crankshaft, connecting rod, connecting rod pin, and maybe the piston. Good Luck!!