The fps is abit low, it might be short stroked.
As for its internals I could only guess (am on my mobile ATM).
If it is short stroked, its possibly a low ratio/high speed set up, with a high torque motor, or it could be dual sector (I think that's right) gearing.
When I finally get a new 8mm gearbox for my mp5k, I plan on 13:1 gearing, lonex a2 motor, with a M120 spring, which should see me to 300fps, and 20-25bb/sec. Don't know if I will have to short stroke it or not yet.
As for the best motor, from my reading, systema (£80+) then lonex (£50+)