I had a set of B&B cat backs given to me to try. No cost. At first I loved them, but the resonance became so bad that I hated them. I contacted B&B as well as others did, and B&B replaced them with a new set. Seems they had trouble with the deflector tabs being placed at the wrong angle. They now have a template to assure their mufflers adhere to their standards. My new B&Bs are fantastic and I love them....NO RESONANCE!!