The hole when inside will be just up by the heater fan. You can drill it and get to the hole without destroying anything. I'm not at home so I can't post a pic of where to drill the hole.
Maybe someone with a Gsr shell can post a pic? I think it's for the abs wiring?
There maybe a embossed oval where the cutout goes, I can't remember. I know I didn't remove guard or anything, just the rear half of the liner to get access with the drill.
There is 2 options with the mtx, one has a longer lead than the other for the same price. I got the long lead version, don't know if the short lead is too short or not, but why would you get a short lead if it's the same price as a long lead. There is a couple of loops of lead under the dash but I'm fine with that.