I am new to this and am trying to get my check engine light to stop coming on with rear 02 codes. My Truck is a 2001 Silverado 5.3L Auto trans. I installed headers & air intake system and removed all cats. Truck runs great but keeps setting rear 02 codes. Rear 02 are still plugged in and tied up on frame. I also installed 5:13 gears and now get the abs & brake lights coming on at times. I cannot seem to find where I would make these changes in my tune to fix these two items. Any help would be awesome.