I want to get my airsoft well g3a3 sas up to 375-390 fps?

im thinking about getting a 6.01 tightbore 590mm with a (H-E-C-K of a) silencer and i need more fps to really use it to its full extent and ive heard the well g3a3 (the gun im talking about) is not a amazing gun for upgrades but i aint buying another gun that cost more so i was thinkin gears and a piston and a biger spring and shims and bushings but i allso need to know what gear box type it is and a link to a video of people working on it so i dont got to pay $55 so i'd love any links to gears pistons shims videos e.c.t. i would prefer not to get over 405 fps but if thats what it takes i'll have to work with it and how acuate will tight bore make it? sorry for bad gramer did it quick. but hey... im texan. thanks for your time and thoughts please comment