I've been doing a bit of work inside my dash recently, and I noticed that the JB HiFi guys who installed my head unit had left various bits of wire, etc which may have rattled. You can make a big difference by getting in there and putting foam around anything that might ever make noise, and cleaning any rubbish inside.
Jack Travis, E-Series Acting President
1989 Ford Fairmont Ghia turbo/GL replica (underway)
1994 Eunos 800M
1990 Ford Laser S