My friend had a Geo Metro and I used my dad's Lumina to demonstrate what his Geo Metro MIGHT do with a really powerful stereo system. If you've driven a Lumina, they have VERY touchy brakes and they got very decent power in the engine. So I used both to demonstrate the effects of very large bass notes hitting with that little 3 cylinder engine. He didn't really appreciate almost hitting his face on the dashboard. But he got the point.
These are really good tips, by the way. This is simple shit! If I can modify the wiring diagram for my headlights and do a successful rewire job while bypassing most of the van's old electrical system and end up with brighter headlights, I can definently do this.