Reviewed By William L (Superior, WI) Reviewed for a 2003 GMC Yukon —9/10/2015 5:58 PM
WoW! I went from 12.5 to 16 in the city, using 91 oct on performance mode, shift points firm. Versus 87 oct in stock. It's how you drive it that matters. The driving coach is way cool. And it's fast too!