What is the consequences of gutting the Catalytic Converter in a 1999 Honda Civic?

 

Your exhaust might smell a bit worse, and depending where you live, your ride won't pass an emissions test.
Your engine might run a bit better since there won't be as much exhaust restriction (maybe a bit more HP).

 

I believe Sacicons said it would actually disrupt your exhaust flow and cause a drop in exhaust velocity resulting in a loss of HP and more importantly increased emmisions. Isn't your car OBD-II with (2) O2 sensors? Wouldn't gutting the cat cause a CEL?

 

Here ya go.......read up on this prior thread. It should answer your question.
https://www.hondacivicforum.com/m_54818/tm.htm

 

its never really a good idea, but its a horrible idea on an OBD2 car. it will set off CELs all day.