The rear shade shouldn't scratch the tint. If you look at the shade, it actually has little rubber wheels so that is rolls up the rear window. I use mine all the time and it hasn't affected the tint at all.

I wouldn't put any stickers on the iside of your windows though. If you ever wanted to remove the thing, the tint would probably go with it. If you really want to put something on, i would suggest to do a decal on the outside of the window.

 

oh, i guess i should've checked to see how the sunshades roll up before asking my bad.
but thanks for the reply.
i probably won't do any decals 'cuz i'm not a big fan of them anyway; unless i found something i really really liked (maybe a "newsradio" sticker..woo!).

 

I just got new tints on my 01 I30. 25-rear & 35-front for $160 with lifetime warranty. I think they did a real good job. The dealership I bought it at wanted to charge me $400 for the same job.