I got a beefed up pump linkage for mine in conjunction with a flat piston an valve. I also put a lighter spring in the valve so I could run a lighter hammer spring which improves my modded trigger's pull. I also decreased the valve volume so it builds pressure faster with fewer pumps. I have not chronographed it in awhile but it kills head shot rabbits and squirrels cleanly. It is also very accurate which allows head shots on pidgeons. Best of all, with a homemade can it allows all this in town