i find that I run my Twist with the .46 AX at half throttle all the time. Any muffler is fine, but if you want the performance back, you can open up the outlet a bit or even take it bigger than the OD of tailpiece/stinger if there is no noise rules at your club. You will lose tank pressure though so throttling may suffer if you have a larger carb. Our control line stunt planes were drilled out quite often, no throttle there. That was when mufflers were a new thing, and robbed a lot of power.