Super Six install on 1974 Dart

The SuperSix engines didn't use a 2 1/4" exhaust system. The exhaust manifold outlets were roughly 1 7/8" in size, the same as all the others. The outlets also have a roughly 5* tilt to the rear. This may have more to do with exhaust routing to catalytic converters then any performance benefits.

The best bang for the buck, is installing a 2 1/2" exhaust system. This will wake the engine up, as it allows it to breath.