Definitely uncommon flange that's on there now. it's pretty beefy just no clue what it's for.
I think I've got it figured out and you're supposed to weld on the flange that comes with the wastegate. It seems to have a valve seat machined into it and that would make sense to me. There's tons of info on how WGs work and theory behind it but very little I've found on this is how you actually install one, bolt this to that, weld this to that, etc.
Guess it's off to the welder's tomorrow.
97 RSP SC300
Z06 / TT BBK | 19" CCW SP500 | Tein CST