Are you serious?
ALL aftermarket Mustang exhausts drone.
I've just ended 15 years with Borlas & Magnaflows.
The people who say theirs don't are 18 year old heavy metal fans who are already half-deaf.
Even the stock mufflers have a little drone, but it's liveable.
Some drone between 1800 and 2200 for me....seems to be less after 5k miles. They sound very good and I get lots of complements. Very well constructed and easy install.