My truck is a CA truck and has two catalytic convertors and I was wondering if it's necassary two keep both. I figure one should keep the exhaust clean enough for Colorado emissions and I could free up some mid range power by eliminating the 2nd cat. Will this work or will it throw a code or will it not just run right without the 2nd one not in place?

 

If it's after the O2 sensor, it should be ok.

 

The previous owner of my truck had one of catalytic converters stolen so he upgraded system to federal standards and added a magno flow exhaust. The up and down stream o2 sensors were changed to federal standards.

 

A Cali. truck will normally throw a P0420 without both cats. In fact, it frequently throws the code even with two, if they are after-market. It will run just fine.