How to return computer to stock programming?
 

I traded my 03' duramax 2500hd recently for a nicer lower mileage 05' fully loaded. Unfortunately I find that this truck has way more power than my first, around 5 mpg worse mileage, and aftermarket stainless exhaust w/dual outlets. The tires are the same ones on my 03/ there has been no change in ride height, or other modifications. How do I remove this performance software? I have a good warranty the head gaskets were just replaced because of mild seepage. I want my mileage back, I don't want or need any more power than stock. I want mileage!!! Would a water/methanol kit improve my mileage enough? I like the lower EGT's with the kit. How do I find out if the trans was modified to handle the upgrades the previous owner made? I have phantom electrical issues with pass rear power window, and factory cab lights allowing golf ball sized rust holes in my roof and dripping rain off headliner. I'm cutting and welding a replacement sheetmetal panel as we speak! My growing concern is that I may have to trade this away if I cant remove the programming!!! Any advice would be greatly appreciated.....:humm::argh:

chevy dealership can return you to stock, after that,..... just personal preference but hypertech makes a mild tuner, very inexpensive and u get about +3 mpg on their mild tune. also look at getting a new turbo mouth peice, (kodiak lbz is about 100$ and it doesnt have the pcv port) maybe mod the stock air box, i cut a few extra openings so i could get a wee bit more air and threw in a k&n drop in filter. Does your exhaust have a cat or muffler. I know in most states its not required for a diesel to have either. so look into that, because it will help ur turbo spool a tad faster and allow a wee bit better mpg. i am running stock exhaust, just cut out the muffler and cat but with all my mods im seeing about 16.5 in tow and 20.5 highway