there are 2 variants of the 3SGTE CT26. well, 3 technically. there are 3 generations of the 3SGTE
1G; single scroll CT26, smaller exhaust AR, same turbine, smaller compressor, same cold housing
2G: twin scroll CT26, "larger" exhaust AR, same turbine, smaller compressor, same cold housing
3G: referred to as the CT20B, but not a real name used by toyota. thats about all i know.
I had pondered a Sequential 7M-based CT26, except using the 1G 3sgte hot sides for quicker spool on 1.5L exhaust volume. 600rwhp on pumpgas would be the heat!