Some of the mufflers sold for the large engines are only collector manifolds, not really mufflers.

We had a guy with a Zenoah powered Snapper with a 90 degree manifold. On the ground, it was only about 105 dBA at 9'. If the short stacks from the "muffler" got pointed at you from as far as 120', your eardrums felt like they were about to break, and your joints hurt. However, when asked if he couldn't find a working muffler, his statement was that any muffler quieted those big engines, they robbed too much power!

We lost a racer over the muffler issue once. He was running a collector pipe on a ST 40 rear intake racing engine. The club had the muffler rule in place for over a decade at the time. I approached him about it. We had just recently come to a satisfactory conclusion to some noise complaints from neighbors. He got mad and never came back. Didn't we realize that a muffler for the class he raced in would cost him 500 rpm? It was more important for him to keep that lousy 500 rpm than for us to keep the field.

In the 50 year history of our club, we lost one field because of noise, and spent over $4000 to rearrange our last field to keep sound level at a complaining neighbors property line within the community's sound level statutes. After the rearrangement, we lost several members who couldn't understand why they couldn't fly over the area where we had flown for years.

Noise level is only part of the problem. Sometimes minor problems get blown up by some of the personalities that stick their two cents worth into the issue. Aggressive people who "Aren't going to get pushed around" frequently do, and take others with them.