I used a Slimline Pitts muffler as well. chopped the pipes closer to the cowl. I have a Great Planes P51 ARF. Been flying this model for years. I use the Pitts muffler there as well. Never plugged the pipe and runs fine. What did you use to plug the pipe? May try that if needed.

There is no information on any control surface throws for this model anywhere on the instruction sheet. Someone here suggested throws, but I don't know about Elevator throws 15-20mm. Seems quite a bit for this model... I would think 8-12mm might be a bit less sensitive. Any rate, I always setup for initial flights with at least 2 different throws set in D/R with 50% Expo.

Anyone have practical results for the throws from flight evaluations?

I setup the ailerons for just 5% differential for first flights,