Check out how to upgrade the sound system in your vintage Mustang, only at Mustang & Fords Magazine.
Ford Mustang Six Cylinder Dual Exhaust Borla ProXS mufflers. Then when I want race car sound at the touch of a button I have it, with the cut outs.
It's a 66 with a I6. It starts tapping as soon as the engine turns over and increases with RPMs, so I'm thinking that this a valve problem. Has anybody had this.