My 2007 Envoy was using about a quart of oil every one thousand miles if a majority of those miles was highway it seemed to use even more oil. I have put on about 700 miles after installing the chip and the dipstick reading shows no oil use so far. Also noticed the rpms at highway speeds run about 200 lower than with the active fuel management putting engine down to 4 cylinders. Noticeable power increase and computer miles per gallon readings have gone up a little.
seems to do the job
I purchased this for my 2003 Envoy XL 4.2L V6 for towing mostly. I also have a K+N cold air intake. My wife and I have noticed a difference in shifting gears, lower RPM's in regular driving and towing, more power where it needs to be, but have not seen a drastic change in fuel economy. Have only had it installed now for 3 weeks. I would certainly recommend this to anyone.
Jet performance module
It works as advertised and I'm happy with it. However, getting that damn thing in was a nightmare. Because the connector sticks out further it is all but impossible to get the computer back in it's fixture and the cover for the connectors has to be modified to fit also. No where near as easy as the advertising says it is.