if u apply it on the outside it mght peal off after a while or get chipped just like paint, however i wouldnt even try pulling the au lights appart ... i had a broken tail light and there was NFW i could get that thing apart .. Good Luck
Apply it to the outside.
Make sure the taillights are *squeaky* clean and free of any grime or dirt ( id also recommend sanding back the lettering on the lights as it makes the job look a little neater ). Final clean should be with some alcohol.
From there, be sure to mask of any areas you dont want tinted. Then spray it on in multiple *thin* layers. Imperative it is thin - less runs and crap like that. And allow it to dry between layers. Using lots of thin layers will also allow you to accurately get the "darkness" you would like.
If you do it right, then peeling will not be an issue and you'd be bloody unlucky to get noticable stone chips that high IMO. I did this with a previous road car which was not done overly dark so I didnt have any police hassles, but my mate decided darker would be better and was pulled over and yellowed pretty quickly. Also if you have a rear end accident, your insurance will not want to know you and you'll be left holding the can. Just bear that in mind....
The can stuff is more like paint. And u spray it on the outside.
Did it to my EA.
I was going to recomend u try stocking first aswell.
Sounds ghey but i did it to my last car and it looked ok. Had a few enquiries from ppl at the last cruise.
And its a whole lost cheaper than new lights if u get yellowed!