Race pipe only section to use with CTS-EXH-DP-0013 To remove the CEL that will occur, proper tuning software must be used. CTS Turbo recommends choosing a High Flow Cat for the sake of our environment! Use of stage 2 software upgrade is strongly recommended. NOTE: not a turbo-back conversion part. Only use as replacement for existing parts. Stage 2 software is required to avoid check engine light.