Well. Assuming you still have not put a catalytic converter on your car... your simply not going to pass without it.

I personally deal with failed emissions tests almost on a daily basis. I find that amongst all aftermarket catalytic converters, WALKER is the best. I suggest getting a universal walker converter,(100-150$) install it, even temporarily with weld in flanges if you like...

Take the car out before the test, get the cat good and hot and see what your numbers are from there. If you still fail, post your results and I am POSITIVE someone on this board can help.

PS make sure your EGR valve and solenoid are hooked up properly as well.. If you do not have an EGR valve installed anymore, HOPEFULLY you have some tuning software that will allow you to retard your timing for the drive test (under load) This keeps the combustion temps/pressures a bit lower hopefully enough to keep NOX down on the drive test. (FWD)

just a thought