FYI, I took my noise meter out in the plane tonight to identify my own noise levels. PA-12, 160hp w/8242 prop, and a Hot Rod muffler. 1200 rpm warm-up 85db. 2450 rpm cruise 98db. Full throttle 2700 rpm cruise 102db. Driving home in my Duramax pickup, 65db at neighborhood speeds. Turn on the amplified Alpine and turn it up to comfortably loud volume, 95db with peaks to 99db. My ANR Gallet helmet is supposed to have about 30db of total noise reduction. My stereo? no hearing protection there. I think I know why my ears ring.
I did not establish pre Hot Rod noise levels in my -12. I wish I did. Anyone at Hood with a stock muffler that wants to measure that exhaust's noise level can PM me to borrow the meter. I'll measure the 180 for noise next time out.