I just bought a box lot of muffler Stuff off Ebay . I bought it for 2 nos vintage Mac's mufflers one is a strap on that fits my Veco .61's perfectly The other is the same muffler  but a bolt on that fits my newer K&B .61. I am thrilled because these don't come up very often. There was also a DuBro strap on muffler with thin little pieces of sheet metal with spaces in between them a lot like a super trapp motor cycle muffler, I have heard of these plugging up with castor but I think with the 50/50 fuel we run that shouldn't  be an issue. Any one ever run one of these on a stunt engine and how did it work ? Thanks T.J.

Here it is , I ran it today on one of my Veco 61's, some black crud oozed out of it for about 1/2 a tank its about as loud as a regular tongiue muffler. I figure the 50\50 fuel should keep it clear. T.J.

I ran the Mac's muffler on one of my other Veco 61's The venturi was way to big .335, I Had to put the carb on it to get it to run . The engine with the tube muffler ran a lot smoother, but I haven't done any real work with these engines as far as venturi's or compression. I am just tinkering for now , I don't have my plane built yet for one of these , its going to be a Pat King Giant Super Combat Streak. T.J.