Strange that our experiences are opposite, I don’t have any drone at all, at any rpm or speed including on the highway/up incline. When I first had it installed I thought I did have a drone but I crawled under to look at a few things and found that the exhaust had come loose at the connection point forward of the suitcase muffler and it was rubbing on a crossmember, I tightened and adjusted it off the cross member and it went away and haven’t had an issues since. My wife still thinks it’s to loud in the city, I think it’s a perfect, more muscular tone but it’s her car so I just swapped back to the stock exhaust and she’s happy again. Will be listing my performance exhaust for sale soon.July 8th - Update on the GM/Borla. I just finished a 2,500 mile road trip. It has an awful drone from 66'ish to 77'ish on the freeway when the motor is under light load. It may be tolerable if its a flat road with no wind or downhill....its unpleasant. It'll go away if it kicks down a gear but a slight hill creates that deep wha-wha-wha noise, it's sooo irritating. I'm surprised my wife hasn't complained.
Again, 78mph and above, it goes away and is silent at 80-81 which most of the trip was. Below that, has a nice rumble. Live and learn, last time I buy a Borla system, I've been burnt twice now.
I stand by the don't purchase opinion if your taking road trips.