So I got my special delivery 2019 G Quadrifoglio a few days ago. Order was placed in the third week of Dec. 2018. It came sooner than I thought!!
I don't have a frame of reference regarding exhaust sound compared to previous models; but, there is a significant and unique growl in D mode compared to A or N in which case there is no growl. It's very similar to what I hear in R, but this kicks in a bit in higher rev/speed in D. So the question is if this is the case with 2017-18 models or this is something that got added to recent productions cars.