I have the S type and do not have drone. However, I could see where there may be drone if you have 3.92 gears or 3.21 gears and travel in 7th gear lot at highway.
My exhaust is loudest around 2000rpm or so. If i'm cruising at 70mph in 8th then there is no drone. If i'm cruising at 75mph in 7th around 2000rpm, then it'll be slightly louder in the cab while at this rpm. Not exactly drone, but I could see how it's perceived as drone.
Overall it's quiet at highway, loud under acceleration and cold start, and quite in eco mode. Sounds good. Very musical tone.