Does anyone know where to get some good headlight sealant? I've heard of some kind of rubber that would be better than silicone..
You could try "GOOP MARINE" (blue tube). Clean the edges (use lacquer thinner on a rag (just dampen it). wipe down 'seal' area. flip rag a rewipe. Work your way around seal carefully. When its clean, using toothpicks (the flat kind would prob work better), apply the GOOP carefully and spread with the toothpick(s). GOOP can be kinda 'stringy' so watch for that. It sets pretty quick (30 minutes) and cures in 24 hours (at 70 degrees).
It will dry semi-clear (cloudy white) and can adhere to most everything (including rubber) and its paintable when cured. I have not noted any exceptional shrinkage on projects over a year old. It remains semi flexible (I.E. does not get brittle). An if you want to get it off, you can do that (granted its a bit of work, but I have done it with no damage to the work piece).
If you want something with very (repeat VERY) aggresive sealing and adhesion, at a body shop supply, get the stuff they use to seal automotive windshields. BUT! be warned. This stuff is nasty to work with and you could ruin your work piece if it gets away from you.
FYI: Silicone has almost no adhesive properties. And you MUST get all of it off before trying to use anything else as the silicon will prevent anything else from adhering (unless its more silicone).
Good luck with it. Sure wish I could get some real HIDS for my 07.(sigh)! [bigcry]