[Kos-Mos]

Do you want to field your gun?
Yes?
Leave the FPS like that. Most clone L96 have a "magic spring" in them. They shoot high without the hard to pull spring.

Now if you want to enhance the accuracy, start with a new hop-up chamber or TDC mod. The first will let you install AEG barrels and rubbers. It's made by PDI and cost about 80-100$

Then, replace the piston, piston head and spring guide with a Modify set. And shoot with it. It will bring your FPS really closer and silence the gun at the same time. These parts are around 50$

You will have a good start with that.
If you want to bring it even higher (meaning more consistent, not higher FPS), you can install a zero or V-trigger. The first makes the pull insanely soft, but a lot longer. The V-trigger is adjustable, so the pull can be minimal, but the break is really hard on heavy springs. That part cost about 200$

Then, you can replace the cylinder and cylinder head. I really like LayLax' parts, but you can get PDI/Raven if you prefer. Theses will not really up FPS consistency, but they are made to better tolerances than the stock parts and will be more constant and easier to pull. Cylinder and head sets are between 50 and 150$

A good quality scope (not airsoft scope, a real made for real weapons), and good quality rings (again, real rings, not airsoft aluminum crap) will also make target aquisition easier and the image will be a lot clearer. And usually the eye relief is better. That's about 100-150$ for a "cheap" one.

Now if you only want to shoot at targets, just use it that way. Higher FPS = LOWER accuracy. The sweet spot seems to be at 430 fps with .20 anyways.

Also, when you test your rifle power, you ALWAYS use .20g If your gun shoots 450fps with .20g, the BB will arrive with the same energy when using .28 or above, only slower. It will however travel farther and be less affected by wind.