is that a resonator?

 

Yea those funky things work

 

I know this works for drone, but does it eliminate exhaust rasp? Does it quiet down the exhaust?

 

Ya, its just a resonator tube. Nothing more then 32" of tube with a cap on the end and a hole drilled in the tail pipe its welded over. Can be any shape cuz it doesn't actual flow any thing but sound waves. The sound waves go into it and bounce off the cap and come back in to the exhaust pipe at the right frequency to cancel out the waves coming down the tail pipe. It's how Coras mufflers work. This one is on my diesel and it made a HUGE different! But I have a similar setup on my gas truck. Knocked 5dB off the interior noise level according to the dB app I got on my iPhone,

 

nice..