There is a difference with California legal and Federal legal emission requirements. However if the Pontiac Trans Am you're considering by has not had it's emissions system tampered with (no smog parts removed or modified; such as in for performance) and it is either Federal Emissions equipped or 50-State California emissions equipped, it can pass the California smog check and register with the CA DMV.
Ask the seller to inspect the underhood emissions label for Emissions Information. The label should indicate whether the Trans Am is 49-State Emissions legal or 50-State Emissions Legal; either way, since it is a used vehicle being brought into California, it can be smogged and pass the smog if the emissions fall within California emissions cut scores.
A well maintained used vehicle should produce emissions below California emission cut scores. You can look up the maximum emission limits for Pontiac Trans Am of all years by following the link below.
California Smog Test Maximum Limits
