Upgrading an airsoft gun?

I have a Power Extreme AEG rifle with a plastic gear box (i dont think its metal). I want to change the spring to improve its fps from 125 (lame) up to 300 or 400. This gun is not all too good seeing how its my first gun and i bought it at shopko for $40. Do i have to take my gun apart to change the spring and what do i have to do from there? Anyone know?Upgrading an airsoft gun?
I doubt you can upgrade that and even if you could the spring would cost over half as much as your gun.Upgrading an airsoft gun?
No can do. A gun that crappy won't upgrade. Just buy a new one. Preferably gas. If electric, buy from a decent brand this time! (CA, G%26amp;G, TM, G%26amp;P)
No, no way. The guy is right who answered before, the gun would almost explode. 125 FPS to 300-400 is a insane FPS increase, probably more money to upgrade the gun to buy a new gun. You have learned your leason that LPAEGs and brands like crossman and power extreme suck.



Try this for a starter gun-

http://www.airsoftgi.com/product_info.ph



AEG tips-

http://www.shortyusa.com/explain.html?to and Tips for AEG owners