As you try to dance around the test spec, let me warn you that your model should not even get close to failing that type of test.
You didn't mention which state or which type of test but no way will that car with its feedback control lambda system and three way cats ever fail that test; if even close to running properly. (and with a fully warm catalyst)
A car that passes that test with only a set of spark plugs added, has serious problems.
Bosch Master, ASE Master, L1
33 years MB technician