That^^. You can snake all the wires through it without cutting though. I didn't do the swap, but my core support was cracked so I replaced it. I'm not sure about the hood and fenders though. I like the stacked lights, and might do this myself someday.
Also, if your fenders can stay, you will need to flex them out a little to get the core in and out. I think I removed a few fender bolts to help with this.