I have an 03 monte ss can I take my cat off with out an prob like sensors or check eng light coming on

 

You will get a code and check engine light. The rear o2 sensor will detect too much flow if you just put a pipe in instead. You will have to get a tune to get rid of the code. Other than that you are alright.

 

You wont hav any problems ie check engine light my car hasnt had a cat sinse 2002 o2s sense oxygen not flow

 

If it has not been tuned out or in a '00-'03 solved with an O2 emulator or resolved with the anti-fouler trick on the O2, you will more then likely throw a P0420 code.

If you are interested, I should be able to adjust your PCM if needed. Please review my thread below:
https://montecarloforum.com/forum/pr...impalas-42773/