New to cummins and tryin to learn. I have been reading up on exhaust, and I see a lot of people saying that their trucks came stock with 4", and to just remove the cat and muffler, or put in a higher flowing muffler. Mine has 3.5". Theres an all dodge salvage close to my house. What years had 4", and will it work on my truck? If I could get it cheap, would it be worth buying and then modifying? I am not getting radical with this truck. Looking for good mileage and a little moor power. I plan on 4" exhaust, gauges, and a programmer (smarty).