Hi lurchers
I've recently modded a 2250xl I bought from new.
I did a lot of mods to it to see how powerful and accurate I could get it.
After spending quite a bit of time doing most of the possible mods, I think the best were:
1) Replaced the whole valve unit with a modded valve. The modded valves have been bored out to have a larger internal volume compared to the standard valve and the exhaust port has been angled for more efficient CO2 flow through the transfer port into the breech. I think I remember reading that there are different modded valves for 2250xl and the 2250
