Here in Ohio, the standards for my 92 GT are;
HC (hydrocarbon): 123 Parts Per Mile
CO (carbon monoxide): .69%
NO (oxides of nitrogen): 878 Parts Per Mile
These are the limits. If you are faced with a test, you definitly want your
EGR valve working, and most likely you'll need catylitic converters. They
will probably check for them under the car, or have set the limits low enough
that it's hard to pass the sniffer without them. They used to get down and
look here, but not anymore. I have my printouts all the way back to 1996
and I can see the limits for my 84 decreased in 2002. You also want to set
your timing as close to stock as you can, depending on your mods. A healthy
set of oxygen sensors would be a big help too, if you're injected. Smog pump
can't hurt either. On 1996 and newer OBD II cars, they simply scan the com-
puter for codes, but everyone else must entrust their cars to someone else
(making less than $10 an hour) "driving" their car on a set of wasted dyno
rollers at 45 MPH - with no fan and no straps!!!!! It took my 92 three tries
to pass, with MAC equal lengths, Mac cat H pipe, and cat-back, and it barely
made it. My 84 runs cleaner! Oh yeah, fresh plugs, cap and rotor are a big
help, along with healthy wires. Saving my printouts also taught me that
Ohio started sniffing for the NO in 2002, but they didn't set a limit for it until
the last year or so. Good luck, "study hard"! And save your printout. | 
