Ok , so I went to get my car (2005 Pontiac Grand Prix) inspected so I could renew my tags. The guy connects his OBD connector and prints out a form and tells me that my o2 sensor, cat , and evap system are Not Ready. Basically I didnt pass. Ok so I need help locating the problem , I was told that I need to do a Drive Cycle. The problem im having is that the check engine light has turned on about 3 times now, everytime it is a P0420 which basically it is a CAT problem. I turn off the light with my OBD2 connector. I have speed daddy headers, hi flo cat (could be the problem) . Any help will be appreciated I need to get the parts I need to fix the problem and also I need to do a Drive Cycle.