Did you have these items made or were they an off the shelf part from someone like tally design?If I remember correctly there are two sizes of strut mountings on the Granada Mk3 type uprights. The alloy mushrooms I have (see pic) are the smaller size and are 45.4mm diameter. I think the larger size used on the Sierra and Granada Cosworth are more like 50mm. I seem to remember that the sizes on the 2wd and 4wd Sierra Cosworth use the two different diameters.
I used a computer suspension program to correct the original Porsche 996 geometry. I found that it had some bump steer and I wanted to eliminate that. I suspect that Porsche used non-optimum pick-up points to account for deflection in their rubber bushings.^ how did you figure out the chassis pick up points?