Thanks guys, seems like i'm heading on the right direction. Reason i was thinking of going with 2S is the discharge rate of 60C. Plan is/was to run them in parallel and get the benefit of 14.8v but with greater capacity and discharge than the big 4S 40C pack for pretty much the same price. Only downside is that the 2's will be ever so slightly more heavier than the single 4.

I went and ordered up a Grid motor mount with inner last night. Just wandering if the Novak mod 1 pinions will be suitable as i'm thinking of getting the 18/19/20t pack to play about with..?

Any advice on connectors/wiring? I'm looking to get Tekin 4mm connectors and 12 guage wire for hooking the packs up.

Good advice on the diff housing. Seems like a small oversight from AE if there's that many with problems. I'll get mine sanded to flush before fitting. Is the Kyosho gasket recommended or is the std one fine once the housing has been fettled?