My tahoe use to deactivate some cylinders. I hated it! It would lag on quick acceleration (felt like 1-2 seconds to switch back to full v8) and the exhaust note (I have a tame borla cat back) was horrid.
I removed it with a handheld programmer and the can tune got me 1.5 MPG MORE even with cylinder deactivation off.
Its crap in my book.
///RETIRED-2013 AW 6MT E92 ZCP M3/// Black 359M Wheels/BMW Performance Carbon Fiber Spoiler and Mirror Caps/Arkym AeroSport Front Lip/Turner 15MM Spacers/LUX 8 LED Halo/IND Gloss Black Grills, Gills and M3 Emblem/30% 3M Tint/BMW Interior LED/MusicCar Subwoofer Enclosure/JL Audio 12" W6 Sub and XD600:1 Amp/Euro Sunglasses Tray/Ceramic Coated Megan Racing Exhaust/MS TP's/AFe Dry Air Filter/RPI Intake Scoops/Euro MDM/Feature Coded.