It can be made to fit. I think the biggest tip I can give (albeit a little 'off the wall) is to allow the defuser to bridge two chairs whilst weighted next to a radiator for a couple of days as it really helps get the shape required to fit
Nice work, fancy one of these myself.
I fitted Bofi GV style front splitter.
I used hair dryer to help warm things thru whilst fitting.
Did you bond ? Or screw / pop rivets ?
Pop rivets across the top and bolts bottom left and right where all the tension is.
Bonding pretty much impossible in my view due to the tensions involved.
Remove only the marked up section ?
Aye, because otherwise it interferes with the exhaust ‘lips’ on the new diffuser.