(Klaus?) After an "updated programming", some 03s and 04s get 13.5MPG?

[mmayo]

I have had it on my truck (2500HD 4x4 CC 6.0L) since last october (I went with the 93 HOT Tune). It made a world of difference. I changed my shifts at WOT to 5600 and told him I wanted it geared toward power & not towing. With the 93 tune you can get ~50 more HP, and it feels like I got that! It also increased my mileage a tiny bit.

On the H2 I ordered the 87/89 dual tune, and kept the shift points at stock. So depending on what you put in the tank, the PCM will use different tables, and you'll see different results. On the 6.0L engines, with 87oct you'll see ~25 more HP, with 89oct ~35 more HP. The H2 gets much better performance with the 89oct, it doesn't downshift nearly as much as it used to on the highway when it was stock, and according to the DIC the MPG have increased a bit as well.

Lastly, since I see you have a D/A, I put a 50HP Westers tune on my dads 01 2500HD CC 4x4, Since my dad farms and really hasn't found anything the duramax couldn't handle he wanted an increase in MPG. After I put the new tuned PCM on his truck, he saw much more power and got an increase of about 2.5 MPG. We actually raced trucks from 0-100 and his pulled away from mine the whole time after he got tuned!!!

I have also ordered other tunes for friends with different combo's of vehicles. If anyone is interested in seeing what the tune did for my truck in or around the San Antonio area let me know.