took ages, but finally did it
installed my trunk sub
4 gauge power cable from battery using OEM connector
this is a pic from my old car, but i'm using the same cable so looks the same on the new car
then it goes to a power/fuse box
30 amp fuse for JL Audio XD600/1
amp is installed in the OEM Sat module metal frame
and a 2A fuse for the green wire that powers the LC2i
LC2i next to OEM EPS amp (using Technics harness)
10 gauge speaker wire from Xd600/1 to an Andersson connector for sub quick removal, These connectors are used in UPSs and are heavy duty and can take up to 1/0 gauge cable
this way i can remove my sub if i need the trunk space with removing one connector
Sub is a JL Audio 13TW5-3 shallow 13.5" sub (mounting depth is only 2.5"!!)
this is installed in a custom made box firing through the ski hatch
here is the view from the trunk
the sub from inside the car with the seats folded
(notice the bungy cords holding the sub in place)
seats up
only thing left to do is to put some thick foam around the subwoofer so the sound doesn't resonate in the trunk but only fires through the ski hatch
just to prevent rattles inside the trunk etc
the sub is crossed over at 60hz 24db/octave
makes a world of difference to the OEM EPS system
the issue was never power, the EPS has plenty of that
but it was missing that lower bass that completes the picture