Quasi-n00b here (been lurking unreg'd on/off since I got the car).

Given: 1) STi scoop is larger & looks good (so I got one).
2) larger air splitters (ZeroSports, GTSpec,APS) all made for lager IC and
don't proberly mate to the top of the stock TMIC.
3) stock oem insert (diffuser, splitter, whatever) is not tall enough to
seat correctly to the underside of the larger STi scoop (thus not using
full air capture/flow potential of bigger scoop).

I searched & read many links on the STi hood scoop but never found a solid answer to the question I have, which is:
Has anyone successfully modified the stock insert so that is rises
high enough to seal to the inner top of the STi scoop and direct ALL
the air coming in down thru the IC?
(Rt side of insert, of course)

Haven't remove the piece yet (gotta paint new scoop), but looks to me like "back" of inser is just bent over with flaps overlapping the curved "endplates". Why couldn't one
-- cut larger "endplates" with a curved contour that matches the inner form
of the larger scoop, then attach these to outside face of existing plates.
-- attach an extension piece to the "back" so it bends properly over the new
ends and buts up to the underside of the scoop.

Has anyone ever tried this?
It would allow you to have a fully functioning STi scoop and still use the rubber seal the factory installed to seal to the TMIC.