I have experienced the perfect muffler comparison. I have a 46 Ford with a stock 302/Edelbrock manifold and carb. I used Flowtech mufflers on it and love the sound. I have just gotten my 53 F100 on the road with the same engine/induction and the same mufflers. They don't sound the same, not nearly as pleasant as the 46. The only difference is exhaust pipe configuration[ both vehicles have the same stock exhaust manifolds. Exasperating.