Nasty drone slant 6 Pypes Street Pro

I had a local muffler shop weld on a Pypes Street Pro Muffler and dump at the rear axle. I don’t even know if you would call it drone, it’s a loud bassy/subwoofer sound from takeoff to 2500ish.

I e had a magnaflow on an older truck that sounded great and a flowmaster 40 on a different truck also sounded great, but of drone on the 40. But this sounds like garbage! I didn’t even know TTI had a full 2.5” system until tonight. I am strongly considering going that rout and can swap mufflers easy to find one I like.

do you think it’s the tailpipe dumping at the rear causing this noise or just the muffler design itself?