The TurboXS Catback Adapter is required if you want to connect the TurboXS Downpipe to an aftermarket catback exhaust that is not a TurboXS Turboback or Stealthback. The Catback Adapter is not a catalytic converter, nor does it replace one. The TurboXS Catback Adapter is simply a junction between the TurboXS Downpipe, which is shorter than OEM & other aftermarket downpipes, and non-TurboXS catback exhausts.
Part Number: WS-CBAP
Note: Are you using a stock j pipe or downpipe? If yes, the GrimmSpeed Subaru Stock DP to Aftermarket 3 in. Catback Adapter p/n 077046, is required.