Hello. First some info. I have a 2004 Infiniti G35 coupe 6MT. Other than a plenum spacer and an intake, my car is stock. Just under 77,000 miles on the clock. I have had the car a year and a half now, first bought it with 56,290 miles. I live on Long Island in New York.

Now onto my dilemma. Ever since I purchased the car, it's had a very audible rattle that would appear and disappear at idle. You could also get a whiff of exhaust fumes idling with the windows down (especially on startup) but it's nothing too concerning. After looking under the car and doing all sorts of research, I determined that it was the Catalytic converter rattling internally. It only happens on the driver's side.

I had the car inspected a year ago this month (so it's due by the end of the month) and it passed with flying colors, despite my readings and diagnosing that it was the cat that is either shot or nearly there. I did mention it to them, but they told me that they couldn't find any rattling which I believe because there are days where it will rarely surface. Also, it's NOT the heat shield. I know for a fact after messing with the heat shields that it is the cat.

I've been looking at replacing the cats with HFC from Fast Intentions. They are legal for sale in New York and after speaking with Kevin (from FI) over the phone he confirmed that they are still shipping to New York. I also asked him about all the laws and how these HFCs are handled with the CARB crap. So this is where my dilemma really starts because New York has adopted California's smog laws since 2013. This means that aftermarket exhaust parts (more specifically HFCs) require the CARB number on them. Unfortunately they are not CARB approved.

So, my plan is to have my car inspected at the end of the month after I do brakes and fluids and whatever else I don't want the mechanic touching. After it's inspected, I would upgrade to the HFCs as well as put on FI's CBE. I had looked at replacing everything with OEM, but that would come out to at least $2500, new. Used OEM runs me back to my original issue with New York adopting the smog laws because they apply to aftermarket AND used OEM. So I'd rather get everything from FI for $2,000 and not deal with Infiniti.

Can anyone here comment on their experience passing emissions in the past year or two, in New York? If I go ahead with buying a full exhaust (minus headers) from FI and have the car inspected with them on after a year of use, would I be making a mistake? What do you guys do to pass the emissions testing (like swapping the OEM cats back on, etc.) and if you don't do anything, is there a need to worry?

I want to hear from anyone running HFCs, not just people with FI HFC. I'm going with them because their exhaust setup sounds most similar to the stock setup and that's what I want to maintain.