Old vs New Diesel Dually Drag Race

If you want your 6.7 to sound like an old 5.9, then slap a few grand down on a 2nd gen manifold swap. The older 5.9s had the turbo mounted in the middle of the exhaust manifold creating a much more pleasant sound than the raspy 6.7 which has its turbo mounted toward the rear of the engine on the bottom of the exhaust manifold to make room for the EGR cooler.

Of course you can only do this on an EGR deleted truck. The other benefit to the 2nd gen swap is that it flows better than the 6.7 manifold and you have more aftermarket turbo options.