I'm too late to help but I had a buzz but it was due to a loose bolt on one of the brackets. Snugged up the bolt and, voila, no more bzzzzzzz-ing.
Borla S-types sound fantastic, imho, and there is zero drone at any RPM. I swapped mine out just because I needed something a little more gentle on my old ears.
2012 GT 6MT - RTR #59; performance white / charcoal interior
3.73's, AED tune, MGW Race Spec shifter, Airaid MFT, BMR rear LCAs & relo brackets, Panhard rod & brace, FRPP swaybars, MRT a/c H-pipe, LP OTAs, FR GT500 Touring axlebacks, FRPP diff cover, JLT PCV p/s catchcan