Download 2007-UP GMC Yukon Denali Dynatech/SuperMAXX SUV header system Installation Instructions Old System Removal: 1) Remove negative terminal battery cable. 2) Loosen the lug nuts on both front wheels, but do not remove. 3) Open the hood and remove the wire loom holders from both wheel well covers. 4) Raise the vehicle using a floor jack (you must use jack stands to support vehicle while working under vehicle) or hydraulic car lift. 5) Remove both front wheels after vehicle is raised and secured. 6) Remove wheel inner fender panels from both sides by removing quick release plastic retainers and hex head sheet metal screws. Mark them if necessary so that they are replaced in the same position during re-assembly. 7) Remove spark plug wires on both sides from spark plugs and coil packs. 8) Remove bolt from oil dipstick bracket and pull upward gently to remove oil dipstick tube. Use caution not to damage “o”-ring seated at the bottom of the oil dipstick tube. Temporarily cover dipstick tube hole. 9) Remove all exhaust (4) O2 sensors from factory “Y”-Pipe. These are located one ineach side of the “Y”-pipe before and after the catalytic converters. 10) Remove center cross member bolt. The transmission MUST be temporarily lifted & braced after the nut is removed. 11) Remove the two passenger side cross member bolts, one driver’s side (the center most), and loosen the other. This will allow you to swing down the cross member enough to remove the factory Y-pipe.