My Emission Nightmare!!!!

Ok, so I finally went to go get my emissions test for my 91 mm. The last time I went I had a fuel hose loose and it was leaking so they wouldn't even test me. So, we fixed that, put some new spark plugs in, did an oil change and some other maintenance and I thought I was ready. Well, after the test they handed me a failed report. I passed in the HC (hydrocarbons) test, I also passed in the CO (Carbon Monoxide) test, but when it came to the NOx (Nitrogen Oxides) I failed. Now I have been reading all the material and it says that NOx is produced when temperatures reach a high enough level to burn some of the nitrogen in the air.....so I asked my Uncle who is a mechanic and he said to change the CAT...I just wanted to make sure that sounded right to everyone else. Thanks guys.

Things that may affect nox: timing due to the advancement, run too advanced run too hot
Temperature of engine, higher engine temp causes higher nox count
Cat running inefficient, not properly converting gases
Egr opperation, egr cools intake temp by inert gases reinjected into engine. Can't combust therefore reducing heat.

Easiest to check is egr with vac pump. Then engine running at normal operating temperature. Cat does go out and usual cause if egr is operating normally.

Cool, Thanks Ryan.....we are going to check the egr tomorrow and see if it is operating normal, I am hoping that it is because I would much rather just change the cat...lol anyways, Thanks for the input.

Just move 2 New Zealand, dont have 2 put up wit all that bullshit, i run a 2 1/2" pipe no cat and 1 muffler and no engine emisions controles runs mint