Sorry to necro this thread, but thanks OP for the post really helped me.
My Jap import is a little different, was not easy to access the amp, but was actually really easy to remove the trim and access the loom that way.
I will add that I find those splice clip things to be completely rubbish, tried them first but it was just no good. In the end, I stripped a section of wire and soldered it properly - worked first go.
Regarding the remote wire, LVT worked fine for me - but I also have an OEM boot/trunk cigarette lighter which worked perfectly too. Prefer the LVT though as it turns the amp on with the stereo as opposed to having to actually start the car.
