stg1 : STD EXHAUST HOUSING, LARGER COMPRESSOR WHEEL, UPRATED THRUST BEARING (NOT 360 deg) -31 ACTUATOR

stg2 : STD EXHAUST HOUSING, LARGER COMPRESSOR WHEEL, 360 deg THRUST BEARING, -31 ACTUATOR

stg3 : LARGER EXHAUST HOUSING, LARGER COMPRESSOR WHEEL, 360 deg THRUST BEARING, -31 ACTUATOR

according to burtons! stg3 is .48 housing