Here's a shot showing how I made my mounts and the homemade muffler. I'm getting 7100rpm now on a Zinger Pro 18x6. Here's a tip, if your motor starts going rich when you fully open the throttle (4 cycling), clean your spark plug! Mine started doing this with only about a gallon of fuel run through it on the test stand. Cleaned the plug and regapped to .018 and it's running like a champ now. The homemade muffler gave me a little over 500rpm increase.