Here is the map for the Garrett GT25R:
I am looking for a map of that Chrysler VNT.
I would never consider a single GT25 for anything bigger than about 1.3 litres. What would possess anyone to try a single GT25 on 3.2 Six (Porsche?)? That turbo is tiny. I think a GT28 is a good turbo for a 1.6-1.8litre engine. Maybe a 2.0 if it has head flow like a VW four cylinder. I would be tempted to try two of them on a 3.5. Maybe a pair of GT2871s for good drivability, not ultimate top end power, but it would work great on a daily driver level.
I got the GT15 from Garrett. It may have been a GT12, it has been awhile since I looked at it.