Agency Power does it again with their catback system for the WRX/STI. This system features full 3" stainless steel polished piping that exits through their fully titanium race muffler. It is completely TIG welded for added strength and durability. Agency Power has seen a 12whp gain typically with this catback and it will bolt up to a stock downpipe or aftermarket downpipe with no issue. Included is all hardware and gaskets for installation.