I have run out of tricks to try.
If you wanna squirt your GT6 with the PI manifolds, you need to gain about 30mm (1 1/4") at the end of injector number 1. (More if your fuel rail runs further forward of the injector.)
I have my bonnet lifted as high as the slotted adjustments allow (20mm in the hinge and 10mm on the frame). I have sunk the injectors about 5mm, (probably should not have done this) and used adapters for rubber hoses instead of the usual extruded fuel rail.
IT STILL TOUCHES on injector 1 hose!!!!!!
My bonnet is about 30mm above the valance and it will NEVER marry nicely with the doors, sill and scuttle.
DON'T DO IT!!!
or cut a hole in the bonnet.
I don't think you could machine the manifold surface enough to tilt them down enough without running into trouble with the studs. Same thing if you made tapered spacers.
You can see my full frustration and more photos on my blog....
Perhaps if you turned the manifolds upside down..........????????