i installed some s5 tails in my s4 gxl, the lights didn't come with the weather stripping on the top part of the lights. So I have about a 1/4inch gap between the top of the tails and the body of the car. I've looked for weather stripping multiple places including VB. I was wondering if I could use RTV in the little crevass. Would it look nasty?

 

I'd stick with some type of foam-rubber stripping.

Also any water built up behind the lights needs to drain out. I haven't looked but I'd assume the stock stripping has a small gap for drainage.