I have Infinity Basslink subwoofer and bolted the ground wire to a metal panel on the left side of the trunk (the one that has the wire harness on it). I only realized now that the trunk liner would probably be touching the bolt, so i was wondering if it is in danger of catching fire at all? Sorry for my ignorance but I've never done a car audio installation before, and physics really wasn't one of my strong points

 

as long as there is a good connection to the trunk you are fine. the only time you have to worry about fire is when there is a spark. so just scrape it to the bare metal and screw it down nice and tight.

 

Yeah, make sure there is no paint or anything on it, or you will not get a good clean sound.