Any members here do inspections in Emissions states?

I have a few questions, since OBDII equipped cars no longer get the sniffer, mind explaining to me exactly how they determine wether you meet emission standards? I do know they scan for trouble codes, but is there any way for them to monitor NOX levels? I DO NOT have a 'hook-up' for an inspection sticker, so I need to carefully plan out my mods. Casper? Anyone?

I'm looking into doing a set of VT Stage 1 cams and still need to pass emissions.

 

After some research, states that only plug into your OBDII adapter simply check for Emissions equipment trouble codes?

Nice. Anyways, still need some insight...

 

I'm pretty sure that its just OBDII codes, because I know someone whos car was running really rough , and someone cleared out his codes with his OBD II scanner so he could pass and not have his check engine light on.