Why such performance and fuel economy gains with a turbo back exhaust system? It’s simple physics and engineering. The less work your diesel engine has to do to expel exhaust gasses, the better. Your stock exhaust system has multiple restriction points where the piping may reduce briefly from 4 or 3.5 Inches down to 2.75 Inches. Aftermarket diesel turboback exhausts are built with larger than stock diameters. Just as important as the larger diameters is the use of mandrel-bending machines. Mandrel bending is a process that leaves a constant pipe diameter throughout the entire length of the exhaust. This greatly eliminates restrictions, which means your engine can move that bad air out to the tailpipe easier than with your stock exhaust.
Many of our customers come to us and ask “should I get a 4 inch or a 5 inch turbo back exhaust?” The simple answer is to get whichever one you want. Realistically, unless you’re planning on exceeding 600 rear wheel horsepower, you’ll be just fine with a 4 Inch turbo back exhaust system. That being said, with today’s diesel trucks pushing almost 400 horsepower coming off the factory assembly line, adding 200 horsepower isn’t that much of a stretch. It won’t hurt you to have a 5 Inch exhaust system if you’re under 600 horsepower, and you have flexibility in the future if you get addicted to the power (trust us, it happens all the time) and decide to upgrade your diesel more than you originally planned.