I sold my '03 Silverado 1500 4.8L crew cab which was a great ruck for the 160k miles I put on it, and picked up a 2005 Silverado 2500HD 6.0L with 20k miles for towing a toyhauler and a bigger payload capacity for hauling coal and gravel etc. With the 6.0 its a beast, but as we all know the mileage sux. When I first picked it up, I was getting about 11-11.5 mpg using the numbers from the Gas Log app on my droid.

I have tried some of the hocus pocus suggested on this site and I am mildly pleased with the results. Installed a Modified Intake Tube and drop in filter from Airaid, did a couple of 60 mile round trips to work and my mileage went up to 13.2. I next installed a Throttle Body Spacer also from Airaid, and even though its not supposed to help the newer engines the next couple of tanks went up to 13.8 m.p.g. The last thing I did was buy the Diablo Predator. The results were not stellar compared to the price, but still in the positive direction with gains up to 14.5 m.p.g. using the 87 octane setting. Although the gains seem modest, I have a 60 mile round trip 5 days a week, everything should pay for itself in about a year.

Next I was going to try Seafoam. Any negatives on using this product? So far everyone I talked to and forum members all seem to think this stuff is great. I would like to hear the cons of using it if there are any. Thanks in advance.

 

Seafoam is good if you have alot of carbon buildup from running rich, it will clean it out good. Best thing is keep air filter clean, dont oil it that much, some new O2 sensors, and run that programmer on 91 setting. These heads have a 9 to 1 compression. Using super unleaded will definately show better MPG's and more power. The 91 setting will advance timing for more power, but you will need to put a 180 t-stat to keep temps down from advancing the timing. The next thing after that would be headers. I bought mine for $300 and added more torque on bottom end, which is what is needed for towing.

 

Thanks, I will try the 91 settings after I burn through this tank of gas. I'm pretty sure with the Predator I will just have to mimic the injector slope settings I made on the 87 setting into the 91 program. Should be easy enough. Headers will be next.

 

The headers I got for 3 bills are stainless steel, 1 3/4 primaries, long tube and direct bolt ons. They already have bungs welded on for the O2 sensors, and an extra bung for a wideband O2 sensor for tuning. Installation took me bout 3 hours by myself. With your 6.0 it should help her run dam good!