Look at my post on the “factory gm 2” lift installed” thread for a step by step, basically there is a bracket that the mud flap mounts to under the felt wheel liner that can be removed to gain clearance on the backside of the wheel well (side closest to the drivers door) it gains roughly an inch or so of additional clearance. Without it done I could barely turn the wheel, after that I was able to get near full lock. Only having rub in reverse on the front lower valence.
You remove the 3 torque screws on the front side of the mudflap, then remove a 10 mm bolt on the back side. The mudflap can then be pulled away from the truck body and pushed towards the engine bay. There will be another torque screw holding the carpet wheel liner to the bracket, remove this and pull the wheel liner up and away as much as you can. This will give you access to the bracket behind it. The bracket has 4 bolts that have 13 or 14 mm heads. Remove those and the bracket comes off. Then put everything back in reverse order. The final step is to drill a small hole on the back side of the carpeted wheel liner near where it attaches to the rear front mudflap and insert and zip tie it into that new hole and an existing hole on the body near it to pull the flap back. Do not drill thru the mudflap, just the carpet. Repeat for the other side. The whole process took me about 30-45 total for both side and I wasnt in a rush lol
here is the post. Someone else did the write up I’m not trying to steal it as my own just sharing it as it is very valuable when trying to gain a few inches of clearance. The directions aren’t super clear I’ll admit but peel back your fender liner a bit and you will see exactly what it is referring to.