by Mike Mavrigian
(Taken from Performance Exhaust Systems by Mike Mavrigian)
There’s no rule that says a pipe must be round. Specialty dies are available that allow an oval profile to be created.
Why would you want an oval pipe? This shape is favored primarily when you have clearance issues. While an oval pipe can be made with the same cross-section volume as a round pipe, an oval pipe is narrower on one plane, which provides additional ground clearance for vehicles that have extremely low ground clearance (such as many NASCAR applications). This allows you to flow the same volume while providing a more compact installation (relative to undercarriage and ground). Oval pipes are also used on street rods where either ground clearance or appearance (or both) is an issue.
In terms of appearance, oval pipes provide a more unique look to the exhaust system. If you choose oval pipe, you won’t be able to make your own bends, but as long as you can lay the system out using a combination of straight, 45-degree, and/or 90-degree pipe, raw sections are available for you to trim to length and weld together.
There’s no law that says that all exhaust pipe must be round. Oval pipe that provides added ground clearance is readily available from race exhaust pipe makers. (Photo Courtesy Burns Stainless)
Oval exhaust pipe provides added ground clearance while maintaining exhaust volume. Oval-profile pipe is available in straight and angled sections. (Photo Courtesy Vibrant Performance)