Karol, you were right about the 18-6 prop. It is much better, although the one I am using is a 18-6 Wide, I think it may be a touch too much for the engine. I really need to get a tachometer so I can see what it is spinning. There is a 17-8 prop in my tool box i may try that one next time out. I made about 10 flights today with the plane.. WHAT FUN !!!

With the 18-6 prop on the plane diving while at full throttle down to about 1/4 throttle the engine sounds normal, revs up and still makes plenty of exhaust noise. Diving while below 1/4 throttle still the engine goes silent until the rpm drops back down.
One thing to note is that the engine has never died, When it comes back to life after a dive at idle it sure sounds like its going to but doesnt.

Yes I am using the stock muffler on the engine. Would you recomend something else?

Thanks
Ryan