Hi all! First post.

Last night we bought my 16 y.o. son a G35X Sedan. He head his sights on a 350z so he could mod it but we got a sweet deal on the G35 (and I selfishly like them better).

The rub to the deal is the SES code is indicating we need to replace the cat(s). I'm new to the G35 community but this did get me thinking: if we need to replace components there anyway, in what ways can we exploit this opportunity to start him on his modding journey?

So I'm asking the community: what would you recommend? OEM direct replacement, test pipes, elongated Y pipe, ...? Nothing too fancy or expensive but if we can get him some added performance without risking harm to engine components (for lack of back pressure, etc), what are some good options?

Exactly what code is it throwing.

High flow cats are a great choice, I've had good luck with the Fast Intentions RHFC. While you're taking exhaust components apart you should probably replace the factory y-pipe with the HR y-pipe if it's a direct fit for the AWD model. I think it is but someone else might chime in with some advice on that. The stock y-pipe for sedans is a gigantic heavy piece and the HR pipe is both a performance improvement as well as making the exhaust sound MUCH better.

Test pipes are loud, no way around it. Sometimes you can't get the downstream codes to clear even with non-foulers and end up requiring either a tune or a different brand of pipes. The Motordyne ART pipes have a solid history of not requiring a tune.

The code is P0430. Is it more likely an O2 sensor or could the cat be bad?

I appreciate the tips!! Really helpful.

Depends, remove the cats and look inside with a borescope to see if they're melted.

EDIT: Also pull and inspect your plugs, replace if they have 60k or more on them OR if you don't know when they were last replaced. Also check for ANY exhaust leaks at the manifold or cats, both items can cause catalyst efficiency codes.

cleric670 you're awesome thank you. I bought spark plugs to swap them anyway. I'll do all the checks you mentioned and let you know how it goes.