My 2005 SE 3.5 just failed Mass inspection. There were two codes, which I will post later because I don't have them in front of me, but one of them indicates a possible issue with the catalytic converter. Assuming it is the converter, what's the cheapest way out? This car already has the dreaded timing chain issue, so if this is going to be really expensive I have a big decision to make. Thank you all in advance for your input.