I've never had to deal w/ emissions tests before so I have no idea what they involve (this one will be in CO). Can anyone tell me what to expect? I have just a small hole in the muffler right now - will this have an impact on the test? If so, will it fail for sure?

In chicago thy wont even test it.

Wouldn't pass in Texas.

Where I live it's a roll of the dice. I just got failed for a tiny hole in the pipe just in front of the muffler. Passed last year with same little hole, but this time I had a different inspection mech ! Had a big crack in the pass side windshield which no one even mentioned.

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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

I would say It would depend on the brain power (or lack of) of the person giving the test. My buddy passed with a 79 olds delta 88 w/ carbed 350, no cats, no emmisions equip, because the person at the illinios emmisions place only put a probe in one of his true dual exhaust tips. To answer the question maybe, if the guy testing is stupid enough.