I’ve been running Flowtech 50121 Terminator mufflers since 1991, although back then they were called Tarantula mufflers and $70 would buy two of them:
http://www.summitracing.com/parts/BIG-50121FLT/
I replaced the pair once because everything else in the exhaust system wore out and they had multiple adapters welded to them, but the mufflers never wore out.
With a balance tube in the system, to me they sound just like a 60’s era Corvette. Without the balance tube they had a wicked rap at full throttle. Mine are mounted vertically in front of the rear axle with turn downs, and with or without the balance tube they’ve never droned in the cab.