Angels alone are very difficult to find, let a lone Chopayyas. They remove the second to last tooth from the piston completely, and put only 11 teeth on the piston overall, extending the plate on the metal front tooth. Its a piston made specifically for short-stroked, super high-speed set ups, usually in the area of 30 rounds a second. Looks like so:
And I'd highly recommend a few if you can find them. Ive got one in my P90 running a 10.8v, deans, Systema Turbo, and Modify HS gears, (short-stroked), and I havent had a problem with it yet. Still running the original one I got after about 4 months of play every weekend with it.
Excellent idea on the variable voltage settings.. Just for the sake of being funny Id work out how to construct a voltage switch on the receiver, with settings like "meh," "fast," "SHTF," and "Zombies."