...it took a lot of careful and skilled fuel mapping to get it to run right at low engine speed/high load That's part of what scares me... I'm pretty sure the stock ecu from the e34 won't have enough room in the "fuel trim" map to compensate and I'll have to go for a custom-programmed stock ECU or ...

those ports look quite a lot taller/squarer than standard :D do you have the S38 manifolds installed yet, if so how did they improve sound/performance? seems like a cost effective mod to me I still have to get them welded so I don't know yet. I just got my head back together after 5 long months of ...

I'm in the US as well... with an e34,m30 and bought some s38/b36 headers from Germany for the same purpose. Stahl headers laser-cut some flanges for me per specs that I drew up and sent in. My heads are CNC ported so a tad larger than stock. Total cost was near US$85 with shipping, but call or email...