In addition, make sure your car has had a good run before you take it in for testing and make sure you get it in the shop while it's still at operating temperature. I have heard of people leaving their car on the garage parking lot and the mechanic doing the tests with the engine cooler than normal operating range - higher emissions are produced by a cold engine. The Catalytic (sp?) converter is also less efficient when cold.

Another reason to run it hard before testing is that if your car is burning any oil, and you do a lot of short distance or stop-and-go driving, residue will accumulate in the exhaust system and be burned off slowly. If you get it hot this residue will be burned off before emissions testing and will help to lower readings.

Kevin - 1980 242GT