What type of muffler is the mustang mcqueen drives in Bullit?

Steve McQueen's Mustang in *Bullit* doesn't have a particularly identifiable *type* of muffler in the sense of a specific brand or design designation that's visible or commonly discussed. The exhaust system is largely modified for performance and looks, and the mufflers are fairly subtle and hidden beneath the rear valance. They're not a prominent visual feature of the car.