I have them for function, dump bed, exhaust ends in back of cab, no issues with hoist clearance, etc. or moving bed parts. I also haul a goose neck and it gets the smoke up and over it quite well! I've hauled several things and NEVER had a soot coating on them, of course, I don't "roll coal" either! I try to keep mine where it makes good power and not black out the sun! Personally, I think the larger stacks look stupid, especially when I know there is no way they are being utilized, but if that is what you like...I have a 4" crossover box with dual 3" stacks, they are chrome, but that's the way I got them, and they don't seem to be holding up bad (no rust!)