[MultipleParadox]

Inner barrel bore and length
(smaller / longer = more fps)

Hi-flow valves, ready mentioned

Rocket valve; some will yield more output, some less

That's all there is to it
*maybe* a stronger hammer spring

BUT; you don't need more fps
Why do you want more power?

More range and precision? You're looking in the wrong direction

Your fps is already super consistent ; don't go and screw it up.

Range and precision is achieved by consistency in power (air seals mainly) and a good a good hopup setup

A 300fps can easily outrange and be more precise than a 500fps gun

Keep that in mind!