At my field, people often mention noise levels and their choice of a muffler to satisfy noise regulations (something about 92DB?).
However I have never seen anybody coming with a meter and checking noise levels of different planes at the field. Is it something I need to take into account - and how? I have an OS SF-61P waiting for me to grow up. I am planning on purchasing a MACS muffler for it. The SF supposedly is noisier than an FX, and this free-flow muffler will sure make it even noisier. The question is - is it still legal in AMA fields?