[Jayhad]

That's not a PGC 8mm it is the older 7mm version you can tell by the blue anodising. The 8 mms are a grey/bronze colour.

I would use the PGC m80 spring it comes with... I use a M120 and the effecient design of the mech box gives me 21 bps @ 410fps with .20s. I have a magnum motor torque up gear set and a 9.6v battery.

If I was to do a high rate of fire I would use the stock M80 spring, high speed motor, high speed gears and a 10.8 battery. I think if I put a 14.4 lipo up to my gun it would be close to those stats without high speed gears.

the Pro-win can't be compared to regular mech boxs as it is so far ahead.

I will tell you this who ever modded that body to get the mech box to fit is a HACK, pure and simple. there is no reason to grind away the metal body that much.