Cusco Type OS Rear Strut Bar | 2002-2007 Subaru Impreza WRX / 2004-2007 STi (666 541 A)Cusco Rear Strut Bar Part #: 666 541 A Overview The Cusco Type OS Rear Strut Bar is a high performance chassis reinforcement component designed to enhance the structural rigidity of your vehicles rear suspension. Crafted for Subaru Impreza WRX models from 2002 to 2007 and STi models from 2004 to 2007, this strut tower bar helps reduce chassis flex during aggressive cornering, improving handling response and overall stability. It is ideal for