Exhaust: Which One And Why

Using Magnaflow’s 5-inch Stainless System for the Duramax

- Jacob White

If you’re like most diesel truck owners, one of the first modifications you’ll make to your truck is a high-flowing exhaust system. With a cold-air intake and some kind of performance tuner on that list of first mods, replacing the stock exhaust kit with a mandrel-bent 4-inch system just makes sense. When trying to decide what route to take with your truck, it can be tough to narrow down the field and make the choice that is best for you. The aftermarket exhaust market is huge and there are so many options. Is 4 inches enough, or should you jump to a 5? Aluminized or stainless piping? Single or dual exit? Cat-back or turbo-back? Muffler or muffler delete? Let’s dive into each of those questions a little deeper and hopefully help you make a more educated decision before you fork over your hard-earned cash.

4 or 5 Inches

When it comes down to exhaust diameter, for 90% of the trucks and owners out there, a 4-inch exhaust is going to flow more than enough exhaust to meet your engine’s needs. A 4-inch exhaust with smooth mandrel bends and a high-flow muffler should be all the average daily driver will require to reduce EGTs and exhaust backpressure. There are 800+ horsepower trucks out there running around with 4-inch exhaust kits, so no worries there. Five-inch exhaust systems are more about sound; the larger pipe diameter will obviously allow for more flow and may show a minor difference when it comes to EGT control, but it isn’t going to be anything substantial.