Ok, here goes.
Materials needed:
-VW GTI tailights (and preferably the car too lol).
-1+ Can of VHT Nightshades spray tint (approved for off-road use only).
-1 Package of 800 grit sandpaper.
-1 Package of 1000 grit sandpaper.
-1 Package of 2000 grit sandpaper.
-1 can of Clear coat (don't be cheap here buy the good stuff)
-Newspaper
-An outside location (this is preferable, trust me)
How to:
Remove the taillights from the car (duh), using 800 grit sandpaper sand down the face of the lights till not a single spot is shiny, this promotes adhesion (prevents tint from peeling in the future). Sand down the middle little dot thingy (okay you think of a better word for it) till the lines around it are gone. Also, pay close attention to the rims of the lights, they are recessed a bit, so fold the sandpaper over and use the edge. After this, wipe the face of the light clean to remove all the dust (there will be quite a bit). This is what the light should look like at this point.
Sanded:
One of the greatest benefits to using the spray tint method vs. the film method is that the spray tint method allows you to adjust the level of darkness as you go. Apply spray tint in THIN coats, watching carefully for drips/runs, here's what each coat SHOULD look like...
One Coat:
Two Coats:
(Warning: This is where street legal ends...)
Three Coats:
Four Coats: (If necessary)
If you want the tailights to be darker at this point, keep applying coat by coat, keeping in mind that you might want SOME light to get through. (I don't want to be rear-ended, do you?)
After you have achieved your desired darkness apply 3 coats of clearcoat, wet-sand the lights, polish 'em up, and re-install 'em.
For comparison purposes:
Finito!