as Tony says, ram pressure is externally adjustable, and the ram can be easily depressurised, dismantled, and serviced if needed.
the only tuning you can do is remove and throw the piston weight away (a good idea as it's too heavy) and polish the insides, change the seal if you want (but no real need).
My .177 shoots nice and accurate, but the trigger is not as good as a rekord.
I bought it because it came to me at a good price as a bag of bits; I do like it, but I don't see any real advantage in 12FP mode over the spring powered equivilent (HW80), and the trigger is inferior. The firiing cycle I guess is a bit faster, slicker and smoother, but that could be easily addressed with a springer by regular tuning.
HTH - JB
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.