Flowmaster drone solved.

Voetom, I'd like your opinion. I have a 1970 Duster 340 with 833 trans. It currently has OEM manifold,
2 1/2" H-pipe exhaust with FlowMaster 40's and piped to the tips. I like the sound but do have drone at cruising speed. I am redoing exhaust using TTI long pipe headers, 2 1/2" X-pipe exhaust to the tips. Would like your opinion on mufflers. Engine Masters showed that X-pipe exhaust quiets the sound so still looking for that muscle car sound out of my system. Street car use mainly. Your thoughts? Thanks.