[DieselSJ]

My 87 R30 had the factory exhaust when I bought it. Single cat. No air injection going to the cat - air injection went to the manifolds only. I did end up replacing the cat with a Magnaflow high flow piece and my numbers got better. I'd make the smog guy show you where it says those pieces are necessary. You should be able to determine what you need from the emissions label under the hood. Or find a different emissions station.