I'm also undertaking the GTi transplant in my '82 diesel.  My mechanic wants
me to stay with the stock diesel manifold and pipe, but I understand that
this is highly restrictive.  I've heard there are other solutions -
'Rabbit,' but I'm not exactly sure.

Could someone please let me know what, exactly, to look for.  I'd like to
know which particular header from which year of which car.  That way I can
call around and try and get one.  There doesn't seem to be a lot of room
there, so I'd like to get this done while the engine's out.  Also, seems
that some headers go the opposite direction altogether.

As far as attaching the exhaust to the header, what's the best solution -
flex pipe?

What about the 0x sensor, cat, etc?  Where do these fit in?

Thanks in advance.

Jon