Answer:
You mean you want a superb fps? In AEG, you can change the spring to the hardest spring you can have (i.e. M160 or M170). You should have a reinforced gearbox, metal piston & piston head, stainless cylinder, change the gears inside your gearbox to a reinforced one, have a high powered motor, and a good LiPo battery. In GBB, you can have a stronger gas (black gas or red gas). It means you should have metal slide and metal outer barrel. Oh yeah, you should have at least 0.28 or 0.3 gr BBs. Btw, you want to PLAY airsoft or you want to HURT somebody with it? Remember, play safe and fun is our purpose in playing airsoft.