This is a downpipe portion that allows to add or remove the catalytic converter based on your choice in the drop-down menu. Use this part for MK5/MK6 AWD platform with FSI or TSI engines, equipped with CTS Downpipe CTS-EXH-DP-0003 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.