The fender cut difference is like 2" on a K5. I think a Sub is similar, but the frame is arched up higher in the front than in the rear, which accounts for 4" difference front to back. Personally, I think setting the body line completely level still results in a saggy look, so I like to split the difference, so the body line is 1" higher in the back, but the fender opening is 1" lower. You need something so it won't look super saggy once you load up all the gear and family or hook up a trailer.