Could be oil in the loom.
That's a silly idea. The bl/bp have a different flange to the v8- sti and only fit smaller turbos than what you currently have. You want the v8- sti header and downpipe.
I had a ching gate on my wrx at one point which I swapped out for a turbosmart one which was meant to have a 1 bar spring...it was 5 psi. 5psi with a td04 meant lots of noise and a slow arse car.
I would be inclined to think the oil you were charged for was not the oil used in the box. Be it a mistake or something who knows. Or it has an lsd diff requiring lsd oil.
Ring Gerald at Strong for Subaru and ask if they have a 3" Bellmouth do to suit whatever flange you have. Dont faff about on anything else there is no point at this stage.
Cert, gate and fab prob 1k or so.
Just make fart noises with your mouth for the entertainment value. Your car will go just as fast and only you will know you sound like an idiot. 😜
Whatever you do with a ewg now will get done again if you upgrade turbo.
It's unnecessary and illegal unless plumbed in and certed. If its plumbed in properly so it flows nicely you wont hear the difference between iwg and ewg.
There is literally no point in adding an ewg on a vf.
I had 227wkw @ 22psi on 95 with a vf22 and full boost around 3.5k. 3 port with link and internal.
Get a 3 port and 3" turbo back and tune it. Tell them to stuff whatever boost they can get into it before it falls over. Engine will take it providing its in good health.