My truck has a stock exhaust minus the cat. and has an aftermarket flow through 4" muffler. Since the cummins comes stock with a 4" exhaust will I see any benefit from changing my exhaust to an aftermarket such as MBRP, Magnaflow etc...??:thanks:

If you have already lost the cat and have installed a good muffler, you won't see any performance gains by going with an aftermarket 4" exhaust. That's why I decided to keep the stock pipes and add an aftermarket muffler and tip to save money. Spend the money on something else...I am :sly:

the bends in upgrade exhaust are mandrel (spelling?) so they are smoother therefore slightly better flow. Sound won't be much different unless u go to a shorty