Also, I found that if you stay 1400PSI or below, you can get away with the factory hammer spring, or a 2289 spring, to keep a decent trigger pull, and still squeeze a good bit out of it with the 14" barrel. If you don't mind stepping up to an 18 or even a 24" barrel, then you can get even more from the platform at that pressure level. I mistakenly pushed mine up to 1600PSI, and needed the disco spring, which then convinced me to get the AoA adjustable two stage sear to get the trigger back to where I wanted. The closed valve system will respond well from 800 PSI (Paintball tank) to 1400 PSI without much extra needed. The 1000 -1250 range will easily get you into the solid 650 plus mark, for almost 100 shots, with very low SD. Just some of the little things I found along the way. It was great fun to build, and I have enjoyed it greatly. P.S. when you call Crosman for parts, pick up a couple of sets of o-rings, and use divers silicone grease on them, the leaks will disappear quickly.
Let me know if I can help out anywhere, did a lot of learning, mistakes, and finally found my way to what I wanted out of this platform with help from some of the regulars. I thank all who provided insight, and advise.
The previous posters were 100% correct, just use a hacksaw to trim the bump from the back of the factory stock, and it fits right back on.