Wow I spent more time trying to squeeze this air horn in than I spent wiring in the relay, new feed from battery with 25A fuse etc. In the end I had to split the compressor and horn. The legshield just would not fit until I separated the parts! Plus the legshield is a real pain to fit and the fuse holder I discovered had the tab broken. Ahhhh! So couple of small holes and a zip tie sorted that and seems to work well. I also discovered the heated grips had been wired into the usb which I felt wasn't quite right, so I ran a new feed from the battery with a fuse and used spurred off the usb wires with a relay to switch on with ignition.