Hey guys, I just put a four inch exhaust system on my truck that came off a 2005 Dodge Cummins. I put the muffler from the 2005 on but I deleted the resonater that comes on those trucks from the factory. I ordered a 4" downpipe so I have a complete 4" turboback system. I was just curious if any of you guys on the site have done this modification and just wanted to know if it should help my fuel mileage. The exhaust I took off my truck to start with was pathetic; nothing more than a small car muffler that was about 2.5" through. Needless to say, I can definitely tell a big power difference. Thoughts and past experiences would be appreciated. Thanks!

 

my 4inch uprgade helped my mileage, as a matter of fact every power upgrade I have made has improved my MPG as long as I keep my foot out of it.

 

Makes her purrrrrrrr like a Porshe. She's the happiest with a full tank, clean filters, and Lucas fuel treatment, 20 mpg empty with 250,000 miles. The four inch really smoothes things out. Have'nt even touched the timing or fuel plate since new.