Cat clogged?

I bought a used catalytic converter, and when i got it , i tried looking through it and i couldn’t see anyhting. I took it to the muffler shop and they said to not put it on. That it would only hinder performance. The guy said it had 170 000 km on it. Do you guys think i should put it on??

Thanks in advance!

if its clogged then why in the fuk would you want to put it on and lose hp?? the answer to your question is NO:shrug:

You should be able to see light through the pattern of small hexagons. If you can’t see through it, or it looks coated in crap, then it is useless and there is no reason to put it on your car. You should also try and get your money back, because the seller should not have sold you something that is obviously bad.