I decided on the OEM black fender flares. I do not like the look of the bushwhacker flares with all of the large bolt holes and the super large extrusion.
These installed in about 3 hours and required drilling 2 small holes. One on the back on each side under the chassis. Where you are drilling these holes, there are no problems at all and I would not hesitate to drill them again. I used a little black paint to keep the bare metal from rusting.
They are part Number : GM 22966585, I bought them at the Chevy Dealer Or buy them on Amazon Here.
The Grey Squirrel Chevy Colorado Mods 