Well today I shot my Matrix PDW has upgrades and it was amazingly accurate. It got me thinking "I want a better gearbox for my JG" So It has plastic hop up and has the original gearbox. I want a m120 spring at least and good gears. I have been doing some research and was thinking about getting a systema gearbox but for $220 i dont know. So what kind of gear box would be good? What hop up would work with it and keep up with it?