I installed the Freeway blasters which are very similar if not the same thing. I did not have to modify anything, but made new brackets out of 3/4 or 1" aluminum purchased at Slowes. Onec you take stock horns off, you will see why I had to make new ones. The stud on the back of the horns was too short to go through the rubber grommet with washers and all. I then slightly bent the brackets back before installing. With the horns on the proper sides(clearence for trumpet) pushed all the way to the sides and with the angled brackets, there is at least as much clearence as the stock horns. No cutting of anything.