my battery is not so easy to get to but i fitted a battery cut off switch that I use most of the time i leave it and I can still attach a small battery charger to the starter wire
I would agree, the flow of water through the matrix is going to be reduced now and it going to flow though what ever way has less restriction... if that is the fuel heater you will have little heat from the heater
my 90 is an 1985, it has 8 bolts to hold each seat, i replaced the seats for some from an unknown year and they had only 4 bolts but lined up perfectly with 4 of the holes