Don't know of a coil that will raise the RPM. Depending on the age of the motor it may have points in it. If you look behind the coil and see a white, round, plastic fitting behind it with a wire coming out and going to the coil, it would have points in it and would need periodic maintainance, clean, adjust but they start better at low cranking RPM. If you don't see anything, it has breakerless, electronic ign. Top RPM is the same on both. Electronic ign. takes a more rigorous crank to start it. Don't know about the muffler that came with it as I'm not familiar although I would use it as it's probably meant to fit the fuselage with the outlet in the right place. By the way,when you get around to starting it, the Quadras like to start juicy wet. Hope this helps and have fun Jeff. Looks like a good project.