TM Gspec or l96

First off this is not a which gun im thinking of getting the TM vsr gspec or maybe a maurazen l96 type please give me upgrades for each i want it be beetween 480 to 500 fps yes i know that its not all about power but i also want good accuracy not on too much of a budget
tightbore
sears
new spring but wat else do i need
please give me a link to some of the items also if its not much trouble

All that I would get after the above list would be a piston and a spring guide, a whole new cylinder set wouldn't hurt though....

sticks