using quark 125 monstor, which motor?

Yeah, the Neus are nice and I'm considering getting one. For an emaxx, you could go with either a 1512 or 1515. I'd go with the 1515 and assuming that you are going with 4S, either a 1Y (2200kv) or 2.5D (1700kv) depending on how much speed you want. I belive that the 2.5D should be all you'll need for the track and will do well for you if you do ever go to 5S lipo. I think that the 1Y is a bit too hot for 5S, although others may disagree.