cutting catalytic coverter ?

[Bob L]

My cat was broken up inside so I just cut a 4" hole with a hole saw cleaned it out and welded the circle back in. It runs much better but that is due to the broken pats restricting the outlet. Been a year no check engine light and I don't smell anything bad. Of course doing body work for 40 years is not the best for your sense of smell.

 

[MarkZ28]

I remove my cats whenever they go bad ir have tge exhaust off for something else. The old pellet style cats were very restrictive, they were horrible pos. The monolith versions are much better for flow. I still have my cats on all my vehicles now though. The 89 Chevy has the pellet crap but seems to be doing ok.

 

[Schurkey]

Wild Guess: The muffler is WAY more restrictive than a catalyst in good condition.

I'm fairly sure my friend cut the OEM muffler off of his K2500, and discovered that the internal passages were TINY. He has a Vortec 7.4, so it would be a '96 or '97, I think.

He left the catalyst in place, had a muffler shop install a Y pipe and a pair of mufflers where the original was, and he said both power and economy improved, although the truck got louder.