When I had a Sub-2000 I bought a can of Blue Dot to push the 9mm hard and use that longer barrel to advantage. A buddy wanted the gun badly and I sold it before playing with BD.
I recently bought two Hi-Point carbines and will be wringing them out when the weather gets better. Not sure I want to "hot rod" them. If you want to maximize performance, BD or Power Pistol powders would by good choices. If you just want to plink, use your normal pistol load and KISS.