exhaust drone/harmonic resonance

I added Auger inserts-- Patriot sells them-- into the 2 1/2 inch tailpipes on my 65 valiant, From just behind the tire to the rear valance. HAd to trim them down fom 3 inch to 2 1/2 diameter to fit inside the pipe but they take away the drone ... For the days I want to be louder, I take those tailpipes off and put shorter turndowns,which exit behind the rear wheel, halfway to the rear.

Best of both worlds.

The inserts have to be welded to stay in place... but when they are on, my car is considerably quieter, unless you punch it.