Originally Posted by Suthrn
If doing a dpf/cat delete pipe what are the real performance differences in the different size pipes? What are the gains/benefits from going up in size? The obvious negative is price. And does adding a muffler keep your truck from sounding like a party favor? Thanks for any response.
4" is all you really need, 5" is more for sound, looks, and bragging rights. That being said, 5" does sound great on a 6.4L. With or without a muffler is personal preference. Kits with a muffler will get rid of some of the turbo sound (rushing air). If you are just going with the DPF/Cat delete, get the 4". The 5" is more for people who already have a 5" DPF back exhaust.