The catalytic converter you install must be California AIR approved and have an executive order number. Since the implementation of the new STAR smog check program, smog stations are being very careful in ensuring vehicles are equipped with proper/required catalytic converters. The smog check technician will inspect your Suburban's catalytic converter and look for the EO number. If they don't match the required CAT EO numbers for your Chevy, or if the CAT does not have an EO number stamped, it will fail the visual portion of the smog check as an "emissions tamper".
Under the new regulation a pre-OBD II (pre-2009) converter can pass the smog check as long as it was installed before 1/1/09 and you can provide the smog station proof of the installation date. If however the installed CAT was not manufactured or approved for installation on your Chevy Suburban, it will fail the smog check regardless. The following is a PDF by C.A.R.B. explaining the new California CAT law.
www.smogtips.com/Aftermarket_CAT_ARB.pdf
