Someone correct me if I am not correct-Drone is when the frequency of your mufflers match and combine to make this sound that just drowns ur ears. The sound is deep and just in ur head it seems like. Some brands and setups r worse than others. An exhaust can break in to a point. There rnt significant sounds changes after break in IMO.
Side note. I would suggest taking a look at MAC axle backs
2005 Mineral Gray GT:
GT500 Front, Cervini Cowl Hood, 93 Oct Bama, K&N CAI, Forged pistons, Forged rods, Stage 2 VSR Comp Cams, JBA LT headers, O/R H pipe, MAC polished SS Mufflers, Corbeau strut tower brace, AL driveshaft, Tokico Struts, SR lowering springs, Steeda anti-roll bar, BMR adj. upper & lower CAs & panhard bar, 4.10 FR gears, 18" Foose Nitrous wheels, Roush spoiler