I have an 05 G35. After a car accident last year i got a P0420 code. I kept my car as a salvage and got the body fixed. After getting my car checked the shop kept telling me my cat wasn't reading fully bad and to wait. My check engine light came back on 4 months later and again they said to wait. In January it came back on and read bad with the test this time. Dealer parts and labor for the two came to 1,920.00, they didn't recommend OEM parts. I was told it was ok to wait a few months to get this done as there is no clog and should be no back up into the engine. I've shopped around and found a shop willing to to OEM, they are a great place tried replacing my sensors first checking everything. Now i'm reading P0420 and P0430 - We ordered the OEM but it's about two inches bigger and is just going to scrap. so it's a no go. He offered to give me the dealer parts at his cost with no mark up, but this is still a big cost. if i wasn't in California i could get this much cheaper.

i can feel the lack of performance and know i shouldn't put this off much longer. i love my car but feel like now it's one thing after another since it was totaled.

Are there any other options out there that i may be missing?

 

I don't know of a single vehicle on this planet that uses 4 catalytic converters, certainly not the G35.

You might look into what's fouling your cats, likely a poor fuel mix either from bad A/F sensors or a bad custom tune.

 

Well now, hmmm........you could get some inexpensive high flowing catalytic converters which would save you ****-tons of money and give the G a bit more power but na, that's too easy.
I'd hit it with a 250 shot of n2o to see if you can jump start that thing. That blast of power will blow hellfire though the cats, melt the insides and blow'em right through the tail pipes and incinerate whatever is behind the G at that time.
If that doesn't work, I'd try to find a witch doctor and see if that mother ****er can't maybe cast some voodoo **** upon thine G.
If none of that pans out, yes, buy a new car. Sounds like new oem cats + labor will cost more than what the car is worth.

 

The G35 does not use 4 cats, and don't ever go to the stealership they're not worth your time. Just get some aftermarket High Flow Cats and call it a day. Z1 and Kinetix are both well regarded lower cost ones, and Fast intentions & Ark make resonated ones if you're worried about rice/rasp