When looking for replacement horn for my ‘05 240SD, there was plenty of room but the limiting factor was the wiring. My factory horn circuit was 5 amps and most strong horns took much more. So unless I was going to run wires up to the bow, I was limited. I went with some mediocre horn that claimed around 6A if I recall. I gambled and used a 7.5A fuse and it’s been fine over a year. I figured a dead short would blow the fuse anyway and a horn is only intermittent use.