This is an upgraded turbine wheel for Hx35, Hx40, Wh1c, H1c turbochargers. This turbine wheel requires machining of the turbine housing for fitment. This turbine wheel adds flows, helps lower egts and will sustain higher boost pressures over smaller turbine wheels. 10 and 12 blade turbine wheels are available. The 12 blade spools a tad faster over the 10. The 10 blade flows more than the 12 but has slightly slower spool up time.