[yuhaoyang]

systema is overrated?
I've used both the M120 and magnum motors before... The latter is much better, but then again it is more than twice the price, so your choice.
if you want to keep it at 310fps then stick with the M120, if you are getting a m120 spring, then it's up to you... I would say systema magnum. Also, if you are opening up the mechbox, you might as well consider a mosfet, since it's not that difficult to wire anyways, and active braking is awesome. I hear a lot of people saying to replace the pinion gear on a magnum, but mine has held up very well so far.