Now for the good stuff:
54.60mm ^
61.50mm ^
So, 54.60^2X 61.50^2 gives us a trim of 79 on the turbine.
So, it has a cold side trim of 53 and a hot side trim of 79.
I still have to take measurements of the exhaust and compressor side to come up with an A/R for both. When I find out, I will definately post it as it will help both of us.
My plan is to try and find a turbocharger of similar measurements and come up with a hypothetical/guesstimate of the GM3's compressor map.
I hope this helps!!!