To increase your Accuracy you only need to Up Grade your Inner Barrel, Hop Up Buckling, and use quality BB´s with the correct weight for the FPS that you are shooting.
A good and price worthy TB are those from MadBull.
A higher torque motor is not going to increaqse your accuracy, so you can save some money there. To bring your FPS up, install a better Piston Head, or replace the `` O ´´ rings with ones that are slightly larger, giving you a better seal inside the cylinder.
I would not reccomend going to crazy with the tuning until you get your FPS to the level that you want, if you are having large differences in FPS, you may be having some issues with air leaks.