Only reason anyone would have issues passing emissions is if they were running pure SD - there would be a MAF code of some sort to have it in SD mode, so wouldn't pass the OBD check portion... I've done the OS upgrades on the ZL1's - no issues - but I wasn't running it in SD - it was still MAF and this was all before the new built in tool withen the editor... You can run or use either - they'll be about the same to tune in - just won't be using bluecat on the custom OS - of course you don't need to right now anyway