It will be hard to do it ahead of time...at least without turbo there to test fit etc.
if you find someone with the skills to take accurate measurements and is willing to take their mani of the car and help you out, you could do it...i guess creat a jig to hold flanges in place and then just make the runners work

I guess I'll build to the test fit.

I just assumed if the BEGI mani, turbo, BEGI downpipe would all bolt together without mods(supposedly) , if I matched the dimensions, it would do the same.

Easier said then done...lol
But yea, if you can get the right dimensions, even if they are not spot on you should be ok as long as you are not too far off

it is pretty hard to copy a manifold and have the turbo placement exact without building a jig.

here is one i did a replacement for of a greddy manifold:
http://i47.photobucket.com/albums/f1...h/DSC08475.jpg
http://i47.photobucket.com/albums/f1...h/DSC08479.jpg
http://i47.photobucket.com/albums/f1...h/DSC08480.jpg

here is the downpipe replacement and how i jigged it up... i clamped the existing downpipe in place bolted to the turbo, then just basically replaced the cast elbwo section of it.

http://i47.photobucket.com/albums/f1...h/DSC08468.jpg
http://i47.photobucket.com/albums/f1...h/DSC08469.jpg

new:
http://i47.photobucket.com/albums/f1...h/DSC08472.jpg
http://i47.photobucket.com/albums/f1...h/DSC08487.jpg
http://i47.photobucket.com/albums/f1...h/DSC08488.jpg

the entire new downpipe weighed less than the cast elbow.

very nice

Awesome, those piecuts look like they would be a PITA right next to the flange. Your skills with a tig torch are pretty sick.
Now start making affordable stainless pieces for the miata. How much for the manifold you just showed us that you had on the miata?

Pretty cool. Any dyno info of the differences between those two elbows?

the owner also changed the compressor wheel and ported the turbine housing as well... so it really wouldn't be a fair comparison. i don't think he put it on a dyno, but was very pleased with the outcome.

it was a pita to weld...actually, it ended up cracking right at the tightest spot to get at... i ended up re-welding it and also reinforcing that area with a second layer of 16g tube.

the top mount manifold i'm mocking up... i'd have to finish it first, but it wouldn't be cheap. i still have to add the wg.

Very nice work!!! I wanna spill my semen all over those welds!!! lol

I think if Stein gets close enough he should not have an issue as the DP has a little wiggle room. Worst case scenario, mod the DP as well, he has the skill.