You want the turbine as high in the fuse as possible. I raised the elevator servo mount 10mm after my prototype model, but the outer cool wall still interferes with the plate if you raise it right up.
JetCat have the offset mount...so this makes a difference.
Some of my guys have mounted JetCat turbines on the other side of the rails (top in the real world) I guess Jet Central turbines have no offset on their mounts?
I guess is need to measure an exact possible centre for the front of the tail pipe, but I'm not due to start building another of these until I have finished 2 Ultra Flashes I now have to build (and a bunch of stuff to finish too)
I have a friend building one now...I see if I can get a measurement off his. If you were to mount the carbon half duct above the rails, screw the cone to that and centrally mount the turbine in the tube it would be about right.

Dave