Adding a a Agm battery in trunk
I'd check with after market hifi kids - the earlier cars had a monster battery in the boot behind the right rear passenger seat - find it by removing the rear most vertical trim piece in the boot... there's either one there or a massive space...
fitted by grown ups and wired sensibly shouldn't cause any issue - if you need to add silly bass / volume levels, remember you'll be deaf by 40 and or have tinnitus* (which to some is so unpleasant they commit suicide) - before the madness of modern life - just living in a town vs living in the countryside meant by age 50 u will have half the hearing level nature intended - if you EVER hear ringing in your ears after being subjected to high noise levels even fora shirt time, its a sign of permanent hearing damage









