Mgmostic kamay Tx. I am up north in Granbury Texas. Me and four others fly The circle. Toung mufflers. Your running a K@B 40! Never used those engines. But my fleet uses Toung Mufflers. Mostly all Fox Stunt 35s. Personally I like them. I order mine thru Stan in Georgia. He will custom them to your spect. The noise level not much difference compaired to a long muffler. Possibly a little louder on all my Fox fleet. My motors are 50s and 70s versions. Never designed for a muffler. I also have Red Head McCoys but they are stored, just my preference to Fox. I think the best feature is no back pressure. So the Fox runs as designed 4 2 4 break. I use classic fuel tanks that don't need muffler pressure outlet to deliver fuel. But I've herd just install a fitting on the Toung muffler and your going to get good fuel pressure. AJ just to add. Look on stunt hanger. And RC there are several posts on Toung Mufflers. Most say its a real weight saver. But most say the noise level is about the same. To include the now issue on Mufflers are required at most flying Fields. That's another reason I installed the Toung muffler. And some say they offer lots of back pressure. I don't agree with that statement. Just because I get a good 4 2 4 break if I set it up right.thru the venturi and needle valve. Most of my Fox Needle valves are the flat needle.AJ