I had long ago decided to use twin turbos for this project because it seemed cool. Sometimes I wonder. ANother cool factor is the use of twin throttle bodies. Why? Just 'cause, that's why. Cool factor at work. It was pretty obvious that any type of Ford upper manifold was gonna be too big and it didn't have the twin throttle bodies I wanted. So I surfed the metal shops here and bought enough material to fab my own. What a chore. The base is 1/2 inch thich 6061 T6. I cut it to fit with a hand saw. I matched drilled the mounting holes to a gasket. A throttle body hangs from each of the flanges. Each flange is drilled for a pressure tap, one for the fuel pressure regulator the other for a boost gage. To assure that everything would fit, I made a wood mock up fairly dimensional to check hood clearances, etc. Everything worked out pretty well. Prolly the first backfire will explode it! Cause this was my first ever aludimum welding job.
This view shows a little more detail on the upper manifold. The flanges mate to stock Mustang HO throttle bodies. The "notch" that goes from top to bottom is just clearance for tool to tighten the center bolts on each side. I need to polish the beast because it really is pretty neat, hope it works.
Here is the upper manifold upside down. As you can see it is pretty open. No long runner torque tunning here. Just wide open space. I hacked this out using an electric dril, 1.8 inch bit and punching anout a bazillion holes. The I filed until my arm hurt. But it turned out almost as well as a mill job. Even after welding, it is still pretty flat and I think one gasket will be ok. If not then I will have a buddy run an end mill over the base to flatten it out some.
I expect that I will be switching to a truck lower manifold in the future which means that I'll have to do this all over again. But maybe not - maybe I'll use one with only one Throttle body and plumb the tubro piping instead.