I managed to get it fitted.Not perfect but its on there.
We used Yankuirui weather sealant 3mm thick . Ideal and no mess.
Only downside was i let the spoiler slip and it scratched the bootlid.
Oh Dear or words to that effect.
Thanks to all who gave advice etc
Thanks Don

 

At least boot lids are easy to come by loads out there.

 

I have managed to find one tonight which doesn’t need spraying. I will be very careful swapping them

 

First off your spoiler looks genuine. The brake light fitting is a clue.
Second, the bolts are different lengths for different models of STi, V4, V5 etc. ICP explains.
Thirdly, if you can get hold of some NON-SETTING mastic, such as is used yo bed awning rails onto caravans, use that yo seat and seal it.
Remember a bead round where the brake light wires go through, and a ring round every hole.
Don't use Sikaflex or Tiger flex to mount it...if it ever does need removed, you can't 🙁

 

I used a caravan sealant

 

Of a Bugeye?

 

It has a lot more holes very similar to the spoiler