Just simply assure that your vehicle is in great running condition, all emission device installed, and engine properly warmed.
Late 2008 I barely passed because the car was running lean, and an aged sport catalytic converter in play. I passed with NOx just 1 point below limit.
Over the winter of 2008 to 2009, I removed the HKS 550cc injectors and replaced with new PTE 660's (to complement PT61mm turbo), new Catco 3" cat from ebay, removed the full HKS IC setup and replaced with 31X12X3 IC and custom piping.
For emission testing Nov. 2009, I zeroed all the settings on the AFC, dial all knobs on the VPC to 12 O'clock, verified that all emission device were properly functioning, and set the AFPR to 30 PSI with vac. hose connected.
Off to test station with no perturbation or angst, engine warmed, and voila, car passed with aplomb
Now, maybe I'll turn up the boost and see how the car performs again..