Just ordered a set of n-fab stainless and before they arrive I have an installation question. All the research and videos I have found show people mounting them using only the 2 bolts per bracket that go into the pinch weld. However the brackets have two more holes at the top near c-shaped part. My factory running board brackets are secured at both the pinch weld and above that into the rocker/kick panel. Will I be able to only secure these to the pinch welds or can I use all four holes per bracket? Just seems that they are quite heavy to attach to just the pinch weld location. I also noticed while I was under the truck that there are about 6 places on each side that are covered with a square of black tape. Behind the tape there are different sized holes and openings. Does anyone know if this tape serves a purpose or not? Seems like water will just cause it to peel off over time anyway. I would worry that without the tape salt or rock could get inside that hollow cavity. Any responses and help would be appreciated. Thanks