Pypes Turbo Pro

Looking for anyone with experience with the Pypes Turbo Pro. Here's my story: 73 Dart Sport, built 340, 200-4R trans, 3.91 Sure grip. Summit 2.5 exhaust with H pipe. The Summit turbo mufflers sounded great from outside but drone was terrible. Went with Dynomax Super Turbos because they were supposed to be drone-free. Nope, they're worse than the Summit. In fact, the noise is unbearable between 1800 - 2200 RPM cruising. The only time it's bearable is when I take my foot off the gas and slow down, then the drone disappears. Love the external sound, though. The Pypes are advertised as drone free but the company does not answer my inquiries. Any real life experiences? I know this is another muffler query, but I'm tired of buying mufflers that don't live up to their advertising. Thanks FABO.