GT30 GT30R GT3037R GT3076R T3 4-Bolt Universal Turbocharger Turbine A/R .73 High Quality Material, Cast Housing with Durable Steel; Boost Engine Horsepower Significantly Increase Engine Power and Torque Outpout; Maintain Combustion Chamber Pressure and Fuel/Air Load Contructed with High Quality Material; Built for Durability and Strength Capable of Boosting Horsepower up to 500+ BHP / Exhaust (Turbo Manifold) Flange: Standard T3 4-Bolt / Exhaust (Downpipe) Flange: Standard 4-Bolt (Volkswagen Circular Style) Inlet/Outlet: 4.125"/ 2.125" / Compressor Inducer: 57.48mm / Turbine Exducer: 56.27mm / Turbine A/R: .73