I installed the Ambassador horns from Hadley, but no matter what you install on the roof get ready to DRILL. First the headliner has to come down. Not that hard, but take your time and use your head. Find the position where you want the horns-check, check, check and re-check the position on the roof. Use a punch before drilling, and then drill. YA-HOO. The Hadleys had pretty good directions but you can always improvise. I've installed 4 sets of horns on the roof and they came out great. One tip though, check the airlines for leaks BEFORE you re-install the headliner-saves alot of time/trouble. Good luck-Jim