Not sure what the difference is wish I could help there. The spiral gears is more like a 1/1 car and probably wouldn't like going in reverse but other than that I don't know. I can speak for the hyper 7's and they are a drop in like slapjack said. And also yes make sure you get the "tq" model diffs if you go that route. I'm sure the vorza diffs would be fine but the hyper can be had cheaper.