In a RHD
MCS the battery cable runs under the LHS Passenger sill trim panel, see here :-
http://images.caraudiomag.com/compet...board_view.jpg
From an article on ICEing your
MCS
Its the thick RED cable in the photo.
It passes through the bulkhead behind the passenger glovebox (LHD car in photo!) and just outboard of the end of the heater airbox where the rest of the car harness passes through the bulkhead.
I would copy this layout for your AMP feed as by copying the
MCS routing you should have less peoblems as there is sufficient clearance in a
MC.