Suggestions for muscle car sound muffler without drone

Well I'm not sure the crossover carb heat really effect it or not. I ran the Dymomax VT mufflers for most of the summer last year. Drone was reduce as you saw above and it was a nice level, not too loud, for the regular driving. all in all it was good. Well they have gotten louder this summer with no other changes. General level is up and the drone is louder than it was last summer. I did a search on line and others reported increases in the sound level after several months of driving with the Dynomax VT mufflers. Now it's too loud including the drone. So much for dynomax VT mufflers. Not sure why my guess would be changes in the valve and/or the fiberglass like material they used in part of the muffler design.

I don't think mufflers should increase in sound level in such a short period of time. Magnaflow uses stainless steel wool instead of a fiberglass like material. I wonder if this is why.