Mods to get great gas mileage, even thou this was done on an Denali.
Found this on another site:
I did some changes to my '05 Envoy Denali and now get 18.5 MPG city and 24 highway. I read a ton of stuff on the internet and this is what I did:
1- removed the cross bars off of the roof rack
2- installed a K&N filter part number 1009, $70.00
3- removed the mass air flow sensor and punched out the honeycomb
4- I have 275/45/20 General Grabber tires, I inflated them to 45 PSI
5- At each fill up, do it at night, you get more gas than in the heat of the day.
6- add 6 ounces of 100% pure acetone to a full tank 22 gal read about this here. IT WORKS
7- Be light on the foot the tires have incredible roll with 45 psi the truck goes by itself.
8- Use the A/C to get the car cool than turn on re-circulate and turn off the compressor and lower the temp to 60. The car stays cold for a really long time.
http://www.pureenergysystems.com/new...00069_Acetone/ READ THIS
Plus we can now "tune"----------
"Tune" it with HPTuner for 3-5 MPG better with mods to the
DFCO tables, O2 switch point changes, increasing timing, ect..