Installing a Spoiler

hey all,
just got a good deal on a saleen wing. i want to put it on even though it doesn't match(black) and it going to have to come off for paint anyways. but thats a long ways down the road. anyways i remember on my previous gt that there was this material inbetween the hatch and spoiler? does anyone know what to use in its place or if there is a replacement, i dont want water seaping through the holes and leaking into the trunk

lol i was thinking of that, i just didnt want to get knocked fo being cheap/ghetto