Ported shroud compressor housing, allowing for a more efficient compressor. compressor specs: GT30 w/ported shroud .60 a/r compressor wheel trim: 56 trim wheel compressor flow: 53 LB/MIN turbine specs:T3 .63 a/r or .82 a/r 84 trim wheel Water cooled and oil lubricated bearing housing standard. full steel ball bearing cartridge, not ceramic.