I had the BRZ spoiler added to my GTS about a week after I bought it, and had all sorts of issues with the guy using the wrong screws to put it on and even dropping a screw between the two boot layers which left a nice new rattle in my car.
First thing to mention is don't go to Newgel in Fyshwick (Canberra) to get a spoiler added they are a bunch of cowboys.
Anyway, I fixed the dropped screw issue by buying a little rare earth magnet from aussiemagnets.com.au:
http://aussiemagnets.com.au/product/...-Earth%29.html
I then drew the screw out by sliding the magnet along the inside of the boot. It's a really strong magnet and it only took a few minutes to get it out. If you take the black fabric off from the boot lid there is a fairly sizable hole that you can get your hand into and you can easily grab the screw once the magnet is slid up to it.
I also found three discs of metal that the guy had cut out to put the screws in, that he'd pushed into the boot too, and I could get those out easily as well with the magnet.
Now I fixed all those issues he caused I'm loving the new spoiler.
Just thought I'd pass on the fix, particularly for the dropped screws, in case anyone else found a nice new rattle when they had their spoiler fitted.
Cheers,
sigma.