I was talking to my friends over at my LHS about this the other day actually which is funny. I asked them if it is better to buy the RPM products, or the Pro-Trac kit and why. They told me that it depends. Are you a basher, or racer? If you are a pure, no track, big air basher then RPM all the way man. I have heard that the Pro-Trac kit was made to transform the 2wd into an outstanding racer. Yes, the arms and all other pieces of it are very thick, and amazingly designed, but RPM is a whole lot better for bashing purposes. Just my words that I heard. Hope this helped.
- Dom -