MuuMuu101's 68 Dart, A Learning Process...

Back when I first drove mine w/ a dual 3" system behind my 440 it was pretty bad even with large Dynomax super turbos, I ended up adding 18" long 3" glass pack mufflers as "resonators" between the rear axle and the tips at the rear valence.
I was thinking of 18" resonators from Summit if I can fit them. If not, I can always get the 12" resonators.

https://www.summitracing.com/parts/vpe-1793/overview/
https://www.summitracing.com/parts/vpe-1792/overview/