I fly with the Wichita Falls club. I've been to the WAMS swap meet a few times. I started attending when it was at Weatherford but the drive to the new location isn't that much further. I would describe myself as dabbling in control line. We have one other fellow in our group who was an active control line flier. He gifted me some of his engines and a couple of planes when he started getting vertigo (old age sucks sometimes). Since then I have become a magnet for old control line planes with stuck engines. I was just given most of a Goldberg Shoestring with an early O.S. .35. !'ve also been accruing a collection of 1/2a engines through the same process. Once you ever have more than one you become the guy who does that thing. But back to tongue mufflers, It sounds like it is mostly about being smaller and lighter than stock or in some cases adding a muffler where there wasn't one before.