Externally, the Delta Flow muffler doesn't look any different from a conventional Flowmaster. The difference is inside. Here's a pair of 2 ¼-inch Delta Flow mufflers that are 19 inches long. We had these custom-made by Flowmaster for '65-'66 factory dual exhausts with center in and offset out. You'll have to pay more for this feature, but it's worth it if you want to keep the original pipes.