Ford uses two different-size mufflers on Mustangs to help cancel the V-8 resonance that gives the dreaded 2,000-rpm drone. Aftermarket systems use the same-size mufflers to contain costs. And while ...

1 This is the whole Flowmaster Force II system. The only trimming you'll probably need to do is at the collector I union or at the crossover pipe to properly align the pipes with the headers. Adding a ...