What kind of fuel milage have you seen w/the 4" system. Better or worse than stock. Im wanting to get one as long as it dont kill the fuel milage. Thanks for any imput, CODY

Mine droped a little but that might be because I like the sound of it ):h :D

04LLYGMCdmax,

Most customers report MPG gains with exhaust upgrades, nothing to take to the bank but if it flows better and the EGT's are lower it has to help. We always tell all of our customers to not worry about checking MPG till they have run at least two tanks thru the truck after any mod as you just have to play with the mod when you first get it and the MPG will be basically the same or maybe drop a little due to your right foot's habits. After you wear the new off of it a little and start driving "normal" ha ha then the MPG will show up.

If you have any exhaust questions call us or check our site we have all the MBRP products.

Mark @ DPPI

I installed a $ inch MBRP on my 02 Duramax in Nov 04. I recently had it on a long trip from Edmonton Alberta to Canmore and back, about 800 kms.I set the cruise at 120 kms per hour and the outside temperature was -25C. I got 22 miles per gallon. No guesstimate. Set the trip meter, filled up when I needed to, divided the milage by the fuel. In the past, in the winter i would get 18 to 19 driving 110. So I am impressed and in the summer it should be even better.

I got 22 miles per gallon. No guesstimate. Set the trip meter, filled up when I needed to, divided the milage by the fuel. In the past, in the winter i would get 18 to 19 driving 110. So I am impressed and in the summer it should be even better.
You must be using the big gallon to get those kind of numbers :eek:

I figured as soon as I posted it there would be someone who would't believe it. So be it, I check it all the time with a fuel milage calulater and it is correct. Too bad so sad for you. In the summer I can go over 700 kms on a tank, you do the math.

well i just installed 4 inch turbo back and it hurt my mpg becuz i can't keep my foot off the accelerator.:D

I have 176,000 miles on my '02 Duramax and do a lot of towing. I had a 4" exhaust installed on my truck at about 95,000 miles. I picked up a little power, but more importantly I picked up nearly 2 mpg with a DynaMax 4" (downtube back) exhaust. It's a little louder than I expected, but I've gotten used to it and like the throaty sound of my exhaust.

I figured as soon as I posted it there would be someone who would't believe it. So be it, I check it all the time with a fuel milage calulater and it is correct. Too bad so sad for you. In the summer I can go over 700 kms on a tank, you do the math.
I assume this post is directed at me - I didn't say I didn't believe you, just looking for a little more detail :confused: . Your from north of the 49th so I don't know which gallon your using and because of your empty signature I don't know what your driving. It's very believable that you could go 700 Km with a long box truck. I have a short box and can get close to 650 Km on summer fuel but no further, but I also run around grossing out a 9000 lbs all the time too.

I drive a 02 short box crew cab Duramax. Before installing the MBRP I got 24 MPG on the highway in the warm months, I have a westers 80 hp upgrade ECM as well. On Holidays last July Pulling my 30 foot 5th wheel 3000kms form here to Okanogan to fairmount BC and around the Rockies for approx. 3000 kms I averaged 13.5 mpg.I am sure the 4" will increase it some if the last highway driving I did is any indication.

Chappy, do you have an idea of what your mileage was before the wester's pcm was put in?

I would imagine that the fellow named "Chappy" was using a 'larger' gallon! The US gallon is something like 3.84 (or so) litres per gallon, and an Imperial gallon is something like 4.45 (ballpark)!