I never drive my 7AT in D so its not an issue for me, although I agree with the OP. Having said that I spoke with Tony at length prior to purchase and went with 18" resonators to minimize it. This was his recomendation for me based on my expectations, to reduce drone. He never claimed there would be none. I'm totally satisfied with my purchase and service from FI.
OP did you discuss this in detail with Tony prior to purchase?