Try placing your tank on a pad of latex foam 1/2" or thicker and use rubberbands to hold it down. The tank should feel very loosely mounted in order to be well isolated, use a drop of CA to keep the tank and foam in place. Your peak RPM numbers are fine. The jett muffler is no good for this application but their carb may run cleaner at part throttle. Dont worry about glow-plugs, the stock one is fine. The OS-F plug allowed the slow needle to leaned slightly but made it more difficult to hand start. A K&B idle bar plug is most forgiving of rich needle settings.