mharring
New member
I got into a arguement with a friend about how my mufflered 4 inch exhasust is holding my truck back. It wasn't really an argument but more of a disagreement!! Ive got a 4 inch AFE atlas ( mufflerd)with there down pipe as well. My friend tells me that the power increase is huge from a 4 to a 5 inch set up. Honestly im looking to go mach 4 in a 7000 ld truck. Im looking for practical and not obscenely loud. Am i wrong to assume a 5inch straight pipe vs 4 inch mufflerd will net me only a minimum gain in hp? Im really about the fuel economy. Im averaging 2000 miles a month. And do they make a 4 inch dump valve if i am wrong? Just thoughts?