The exhaust on my 2004 dually in the signature below turns the back of the fender black if I'm working the truck hard so I installed one of the curved turn-down tips.  But I very quickly discovered when in really rough terrain (wood cutting, etc.) that exhaust tip hangs down really low and affects clearance.  And one day when backing into a high curb that exhaust tip was the first to hit.  Luckily I was barely moving, so no damage.  At least on mine, that turned-down tip hangs only about 6" above the ground.  One of my neighbors who has a similar Dodge had the same problem and his solution was to cut off the down-pointing section of the pipe.  That maintains the needed clearance but still directs the exhaust gases downward instead of to the side.