I would recommend you call Jack and talk to him direct, if you're looking for Turbonetics turbo info.
With their shift in performance direction earlier this year, Jack should be able to get an exact answer.
Technically in T-netics world, the 60-1 would be next. IE: 60 compressor wheel, with the P-trim turbine wheel. Then the 62mm series, but Jack can get you sorted out with T-netics turbos.
What are you goals?