GFB HYBRID TMS Dual Port 20mm Inlet/20mm Outlet 97-05 VW Golf GTI 1.8TThe Hybrid valve is back! In 1999, GFB's first Hybrid valve pioneered the dual port design, which was so successful the technology has since been adopted by most other brands. By "staging" the two venting outlets, at low valve lifts most of the air is recirculated. As the car is driven harder, the valve opens further and more of the atmosphere venting port is exposed for a louder soundThis Part Fits: Year Make Model Submodel 1997 2005 Audi A4 Base