For you guys all discussing what power plant to run, I would take note of the following statement from Matt W.
Matt - Probably would recommend a 10.5 for something similar to 13.5 in a buggy. I personally run a 6.5 in it and it’s pretty fast. Pro4 4600 will run in it but it has a lot of power and will need to be turned down in the esc.
So my suggestion is treat it like a 4wd buggy for Mod and start with your normal 6.5 / 5.5 and see how it feels. For Stock guys, 10.5 motors. I personally won't have a truck for a few months, but my intention is to try the 13.5 that's currently in my buggy and just swap it over and see how it feels. I'll also try a 10.5 if I have one laying around still. I plan on running a 6.5 in it though because I doubt that we'll have enough initially to split the class into stock and mod.
Which brings me to another point. Since this class is new, I suggest that you get together with people from your track and discuss if you guys are going to run spec, mod, or just open. At least for the first month or two until you can get more people driving them.