Flowmaster drone

I hate my current exhaust. 69 barracuda convertible, stock 318 with manifolds, 2 1/4 into an x pipe with flowmaster 40's to stock tips. Too loud, terrible drone. Would adding glass packs or resonators help?I thought that would be an inexpensive fix. Plenty of room to add them before the mufflers. Would that help or would they need to be after the mufflers?