Its two the same size on RX7s and Supras, 2 different sizes on some other cars.

A bit shit though, hence why its one of the first things they remove when modding RX7s and Supras.
Massivley complex and not that effective, so always binned off once at the limit of them turbos.

Turbo technics did a similar thing for cossies years back IIRC.