Looking for advice on exhaust system.

On the Demon 340 4speed I have I used TTI 2.5” and “H”pipe and the delivered kit mufflers- Dynamax. They fit awesome with the factory manifolds, clean and are a nice set up with factory tips.

BUT when I had the 3.23 gears the mufflers (I’m guessing) made a serious drone noise like a “won....won.....won” at lower rpms in 4th. Mostly like 50mph and 1900-2200rpm.
I changed gear ratio (3.91) and it went away. I could had been my cam - but the Napa exhaust and mufflers on there previously did not do that.

In my 66’ Barracuda with 318, auto and fuel injection. TTI “X” 2.50” system with manifolds, and 2.45 gears. When the car labors, same drone.... same mufflers.

I really love their exhaust but the mufflers are to me “just okay.” Order it with the mufflers you like.
Good luck!
Syleng1