With my Sprint 2 Sports, the first thing to change was the steering servo. My friend at the LHS where I bought mine told me that I would want to do that right off the bat. He sold me a Traxxas servo which I'd have to look up the model, seems to me it was a 1075 or 2075, something like that. I put a spektrum in the other one, an S6010 with metal gears. They are both plenty fast and strong for steering now. They sell for around $50 with tax. I did have to trim the mount a bit to get a good fit.
The radio isn't that bad but I would add a glitch cap. Novak and Spektrum sell them for around $10 to $12. They just plug into the bind channel on the receiver.
The ESC isn't the greatest, but will get you started. You will want to replace it if you go brushless. Depending on if you plan to race, you will have class restrictions that may dictate the ESC and motor you can use, such as in USVTA. I think this chassis will make a very do-able VTA car once tuned and modded.
With the info in this thread you can make a Sprint 2 competitive.