Yet another guy who did this mod and as all have reported before me, it is is very easy and inexpensive. I ended up buying two alarms and the 9-pin connector kit. I mounted both alarms one above the other in the slot under the left side cover. I did not drill holes to use the slot for the original connect, just tie wrapped everything back into convenient places. It works very well and is very loud for sure. Easy, cheap mod. Highly recommended.
2013 Road Glide Custom CVO in Roman Gold/Burnt Emerald, Le Pera Maverick, Vance & Hines Power Duals, SERT, MadStad 13", Kury ISO grips & Scythe mirrors.