This is just like anything else - you have to think about how serious you want to be with it. I have a TT-01 R with a Mamba 4900 on 3s and it's awesome for me. But then again, I don't race. I just do some drifting and outdoor driving.
I will say this though - if you want a sweet car, Xray is the best of the best. Check this link out for more info: