Mike, Totally agree with everything you put in the post about this engine. Just to add my $.02. I found the same trends when I used the Tower muffler on the OS and Magnum .46's and .50's. That muffler is amazing, It will add a little over ,1200 RPM's on 15% Nitro on other engines, over their stock mufflers. But the increase in performance also requires some refined tweaking to get the engine dialed in. The engine picks up allot more RPM's in the air, than on the ground, since the muffler sort of acts like a tune pipe, it will cause the engine to demand more fuel in the air than on the ground, therefor go lean and die, burn out the plug and maybe the engine.

Just for the sake of arguement, I put an OS .46 FX muffler on a Tower engine and found it easier to tune, but nearly lethargic in performance. I too, found that the engine likes an idle bar and a fairly rich setting on the high end and very lean on the bottom, similar to a large SuperTigre engine.

I have had several of these just for fun, to fool around with. I had one come apart before the first gallon, sent it to Hobby Services and got another new engine right back. It worked great, using your recipe. Like SuperTigres and Magnums, these engines need to be broken in and tweaked quite a bit for the first two gallons, but after that, they run like the proverbial scalded ape.

Remember you usually get what you pay for, but if it comes with a long warranty, make use of the warranty. I have had similar problems with Magnum .52's, but with a Tower muffler, good break-in and some patient tuning, they are awesome on power. If you are a Tower member, they usually double the warranty on all tower products, making some of their stuff a very good deal for heavy, prolonged usage.

Good luck and happy landings.