You don't have to pull the guts out, but if you're going to use a starter box, why not pull them out? It reduces weight, and the chance

Good question about the different flywheels. I don't know why they offer different flywheels for the pull start, and non-pull start engines. I can tell you I have the Duratrax 1/10 universal starter box, and the flywheel that came on my RC 10GT Plus works just fine with it.