The installation of catless downpipes on your will result in an inevitable check engine light (CEL) as the DME will detect that emissions are not being burnt-up by the OEM catalyst.  To remove this CEL without having to tune it out we offer the CEL Delete Kit which is comprised of either one or two O2 sensor spacers (depending on whether you have one or two downpipes) that specifically calibrated to comply with parameters for a functioning catalyst.  These install into the post-catalyst O2 sensor bungs on each Downpipe, effectively removing the CEL that would otherwise appear.