The "long" super turbos don't have the drone, but are too long to fit fwd of the rear axle on E-bodies. The "short" super turbo fits, and I got rid of the drone by adding a pair of round Magnaflow straight thru mufflers alongside the gas tank. When you put your foot into it you can hear it. When cruising it sounds good, no drone, not too loud yet my says she can "hear it coming".
IMO Don't buy the 3 inch diameter super turbo, they are just a 2 1/2 inch with a larger inlet/outlet, so the internals are still only 2 1/2 inch.