Some folks say to remove the mud flap but you then are more susceptible to stones and with it on sand blasting. You are guaranteed to get stone chips and possibly a broken windshield plus sandblasting without some kind of protection. The protect-a-tow or similar will reduce both, I made a folding plastic guard similar to Road Masters with fairly good results for 5 years. Then purchased a new Buick Lacross and made a guard similar to protect-a-tow. This by far a much better stone guard and have used it for 6 yrs., easy to stow as it rolls up. IMHO.
Blessings Keith