yeah it is prob resonating with your chassie body. BUt try another reasonator i'm sure that will fix at least some of the droney sounds, if not all. I did this with my prior car which was loud and droney. I got about a 40% reduction in noise, but i did use the one with a swivel type reasonator. Was well with the $100.

One thing take it to a good exhaust place. While i got my reasonator put back in the shop also corrected so mountings on my exhaust. This corrected the way my exhaust vibrated, less vibration which also help lessen the noise.

My original exhaust was done by Liverpool exhaust, then correct by Turbo Exhaust.

Turbo charged me $10-20 more but in the end the job was better and i was more satisfied with the result