From the pic below, the middle one is the one I took off my STI. Got the one on the left from Opie oils and it looks like its to big (width) the one on the rights from Halfords. The one I took off the middle bit (with the holes) goes inwards whereas the other 2 point up.



Are either of them OK to use?

 

The size difference isn't an issue in and of itself, if that's what you're asking. In fact Subaru themselves used to sell a larger oil filter - the small one like you have in the middle was introduced in late 2002 to give a bit more space on cars with the twin scroll manifold.

 

Thanks for the reply,Does this mean i can use one of the larger filters then?

 

Yes