both my underbody lights and my PA speaker switches were ran to under my dash ( by the floorboard) hidden so u cant see them from normal sitting ( i have to feel but I know where they are ) . Can be bought from Radio Shack, all kinds available.
When grounding, any bolt that bolts into something metal on ur engine bay. here Is a trick though, most bolts are probably alittle too big to mount that wire SECURELY, if u want to be extra safe, u can buy these things that look like Captain Hook's hand but with a perfect "C", I have some of those lying around ( sorry forget the name and make of those things ). I like to do things "right", just to make sure they don't come un-done...
basically same thing when you ground your subs amp.
