No it isn't a correct one as said - the cut out needs to be done by the new owner... very carefully!!!! Easiest way is to drop it in place with the top spoiler loosened up... then rest the spoiler base on it and mark it up. Be aware that it isn't a straight cut as the fin base is tapered... so you need to cut inside your mark to take account of this. Cut to exact size and it will look loose. That is the only mod you need to do.

Here is a new gen one... goodness knows what that is worth now!!! £86 back then.