Hatzies 2005 2500HD

[TooTall]

Originally Posted by hatzie

I read the contents of the PCM and saved an un-molested copy to my laptop HDD and a thumb drive I keep in my garage laptop bag so I can go back to the as-shipped settings if I screw up. I have an otherwise un-molested copy with the modified tire sizes as well.

Having the correct tire size in the PCM puts the fuel maps, transmission shift points, and TCC engagement back to the as-delivered from GM behavior. Fuel mileage has jumped noticeably and it no longer feels like I'm pushing it hard to go 65 on the highway.

Change the tire size in the PCM with HP Tuners. While you're in there firm up the shifts, shorten the shift times, change the PE delay, EQ ratio, copy your high VE table to the low VE table.

If you want to see a noticeable gain with out a ton of internal mods, get the 4 bolt intake (08 - and newer) with a LS3 throttle body. 20-25hp easily noticeable gains from that alone on 91 octane.