Just curious here. My exhaust system appears to be stock, but it doesn't really sound that way. I just had my emissions inspection done and the HC or NOx (I can't remember which)readings were right on the boarder. The rest of the thing is stock, too, so I just wondered if maybe a gutted cat would explain the emissions and the sound at the same time.

I'm guessing crawling under there and knocking on it might be a clue? Anyway, if anybody knows please say so!

 

Hitting the cat might work but you'll need another car with a cat to compair sounds, but then again it might not work. You can also check the welds. If they look any different, the cats may have been off. Also, if your cats bolt up to the exhaust, unbolt one side and take a look. With a flash light you'll be able to see the block inside. I beleive the bolts are on the back side of the cat(s). You may need a telescoping mirror also. Other than that...........take the cat off and look.

Hope that helps.

 

You can probably tell a difference in the smell of the exhaust. My freinds cars without them, if it runs parked for a few minutes, you can really smell something just lingering around the car. Kinda a subjective test though.

 

Start the car when cold, smell the exhaust. If the cats are intacked then you will smell a sulfer kinda smell. If they are gutted the you will smell raw fuel.

 

A way to test it could possibly be to unbolt the exhaust from the cat and start the car. If the car sounds loud like open headers... I'd say it's gutted, but if the car still sounds rather quiet I'd say its a good cat in there.