Plain and simple.
-I own an '85 Corolla GT-S with a 4AGE--catalytic converter present.
-It did not pass emissions. 25/25 Test - Failed NOx ppm. Reading was 2795 and 1592 is allowed.
-It passed the 50/15 Test.
For the retest:
-With a 1/4 tank of regular gas--added a quart of denatured alcohol acquired from Ace Hardware.
-Ran the car for about 15mins. I already noticed a difference in how smooth it ran.
-Tested the car: Passed @ NOx ppm 1588, 1592 allowed.
-Done--filled the car to full with gas to dilute what was left of the alcohol.
BAM, done deal.
Disclaimer: I am not responsible for anything that goes wrong with your car. Depending on what you pass or fail, some cars require more than this. I suggest you not run your car with this on a regular basis. I've read that it is harmful to plastic and rubber. If anyone has more info, I'll be glad to edit/add/adjust/amend what I've already typed.