As I am planning on upgrading my Cyma CM.030 soon, I figure I will add to this thread as I do.
I have consulted and followed on Facebook, probably the UKs #1 AEP builder, Sam Liggat, about some upgrades. He has some upgrade AEP motors he has been testing in some builds. Promax Cobalt brushed 370 RC motors are what Sam is testing. There is a torque version and a speed. The torque is just too slow for our application according to Sam, so go for the speed or lower TPA one. Either way, I will probably just be using the can with a armature originally from the gun. The stock motors have the absolute tiniest brushes and horrible endbell design. The Promax is a lot beefier.
Also for batteries to use that fit, you want the highest discharge rate you can. Sam recommends the 300mah 7.4 45-90c that can be found on Hobby King. I actually found these on a whim, before I knew he recommended them.