The elbow doesnt fit, but surely you can just fit the completes ERST exhaust housing to the Cossie T3's, as the wheel is the same size.

I didn't want to do that though, because the ERST housing is terrible and known to have a major problem with cracks around the wastegate. So I developed an adaptor pics of which are in the forum somewhere. This way you get the advantage of the better flowing Cossie exhaust housing, and especially the much better wastegate design.

Other option is, as said, to mod the downpipe.

So, about the Saab stuff - is it basically the same as a ERST housing, but bigger?
Or it is like a Cossie exhaust housing, with the wastegate integrated in the design, which the ERST elbow just happens to bolt up to?