If you have an engine and radio system then the XR8 is the way to go. It's like 50 bux more but It has all the upgrades installed. The stock RTR radio is junk but it does work.
I seem to be having air filter issues with mine, I noticed what looks like black soot in the carb. I cleaned it out and changed to a different filter and it did it again. If you get the RTR one, keep an eye on the air filter.