When I made mine, I considered following the contour of the floorpan, but theres no possible way to go beneath the floorpan without them being visible and losing clearance, as the rear pans and the frame rails are level with the rocker flange. And, to me, 2½-3" more clearance, as well as a much smoother side profile, was well worth penetrating the floorpans. Also, being able to weld the full length of them them to the floors from the front to the rear makes them FAR more effective for increasing rigidity, which is why I put them on to begin with