The key to passing an emission test other that a clean burning and firing engine is to have catalytic converters in working order and running at exactly 14.7 AFR. i have just recently had to do a bit of mucking around to get my car to pass.

First i had high flow cats went in for my test, had it all tuned within 3% on VE table but it was in CL mode anyway but it failed miserably.

Next go i had standard cats back on and tuned it in OL then on the day just tweaked the AFR to be 14.7 using the live slider bar thing in the scan tool to get it to pass.

My question is would it have passed in CL with the standard the cats? or does CL vary to much for the cats and out of there efficiency range of 14.7?? i would think it should just work since standard cars apparently pass it in CL. I wasn't willing to risk it at $165 a test when you cant change CL manually tho.