I agree with abovetherim.

I have the Bosch battery too.

Never let me down even when have left lights on all day.

The battery technology has improved dramatically in the last 20 odd years.

After doing the basics as mentioned earths, cables etc if your worried about flickering headlights and draw on the cars electrical

(they don't have the biggest alternator) you can add some audio capacitors that way if your using amps the draw wont pull so hard on the shared electrical.

Although I'm not sure how much audio will fit in a mr2.
