This is something I wanted to do for a while now and today is the day I did it.
I have 4 different commonly available mufflers that I put on the same tractor, engine, to compare sound.
I don't have a sound meter so you have to use your ears.
Test tractor has a 15hp cast iron B&S engine.
1" pipe threads
made for 16hp Kohler engines in Gravely tractors
Made for 12hp Kohler engines in Cub Cadet GTs, not sure if it's too restrictive for 15hp, 16hp engines???
Used in garden tractors with 16hp Kohlers