I just picked up a mark 5x DSI unit. I have the mark 5 pro on my console already. I use a garmin hand held gps for all my mapping. My question is, should I install the DSI unit on the bow or the console?

Personally, I would put the DSI unit at the console.  I find this technology most useful while idling and looking for places to fish.  Don't get me wrong, DSI functions well up front too.  But, given the choice of only DSI or 2D sonar up front while fishing, I prefer 2D sonar.