Originally Posted by Buzzrexx
If you're going this route, I'd highly recommend changing the piston to a steel-toothed one, and adding a sorbothane pad. Then you can use an 11.1 Volt Lipo battery for some wicked ROF. or you could always use the mechbox stock until something breaks and then upgrade it at that point.
Also, a point if you are adding to the barrel length like I did, (by about 6 inches) you'll also need to get a matching ported cylinder. For now, though if you change just the hopup and the barrel (regular MP5 length), you'll have a very gameable AEG.
Simply changing the battery to a 3500Mah 8.4v won't increase ROF enough to warrant that. I wouldn't suggest to any newb that they run a high speed setup, especially with a V2 gun shooting hot. There's a lot more to making a high ROF set up then putting in a stronger battery.