I just bought a 2008 350z and got a mechanic who is a Z freak to do a quick check over it (Haven't yet taken it to my main mechanic to REALLY get it checked out), and he said there are/is bad cat converter(s). He said there could be loose materials (There is a dull rattling when idle) working their way into the engine and causing some damage, or something along those lines. BUT when I asked my main and trusted mechanic he said that they shouldn't cause any damage and to just run with it.

Is this a serious problem that needs to be fixed, and if so what should I do? I need something relatively cheap (around $1,000 range including installation), but I also don't want to get the wrong cats and end up with a terrible ricer whine. Should I get HFCs? Are the really cheap universal cats any good? What about resonators?

I'm worried about there being an annoying loudness when I'm driving around the city.

 

Changing the cats alone won't alter the sound of the car too much, if you're running a stock exhaust then you still have a resonator in the mid pipe and a muffler, there are ways of testing the cats, with a gauge that takes the place of one of the 02 sensors, the gauge will show how much pressure is building up in the cats, if the cats are clogged and the exhaust isn't able to flow out of the engine the car would be running very poorly and would like throw codes, high flow cats would be a good option regardless, I don't buy the mechanic being able to hear a rattle in the cats at idle, given the amount of things on the car that can rattle, I know the most notable thing I can hear at idle with the car in neutral is the flywheel

 

That's good to know it won't change the sound too much. I haven't even gone to get it looked at and the check check engine light isn't on. I think I read on another thread that there are places that will check the cats for free. Midas or AutoZone maybe?

 

i have the rattle as well on my 08 and i read that you can get them changed FOR FREE due to the govts law. something something 8 year/ 100k miles something something

 

Everything that I have seen on the other threads are saying 85k/ 8 yr. But idk maybe something changed... That would be awesome though.

Actually, it wouldn't matter either way I got like 103k on it.

 

Don't cheap out on exhaust parts, unless you're getting test pipes. Test pipes are test pipes are test pipes. But I would still go with a reputable brand. I personally have had the OEM cats replaced on my 08 and I would sell you mine so I can get aftermarket cat replacements

The cheapest I would go on my car would be Megan. check out t he 370z. c o m or my g37 dot com for some OEM replacements from people parting their cars.

 

I've been thinking about getting test pipes because they are so cheap, but there are a lot of people that say there is a rasp after you hit 3k rpms. I tried listening to video clips of test pipes (with stock exhaust) but I can't hear any rasp, probably because of crappy camera audio...

 

Minimal to no rasp from ART Test Pipes, but they are pricey...

 

Youll need a tune if you go with test pipes too. Figure that into the cost.

 

If there are no other breathing mods, it should be fine without.

 

PROB NAWT
I had a plenum spacer, test pipes and injen exhaust. steady 13.5 af/r WOT to redline

 

I would expect you to run lean. If you test your arf and its fine then sweet. Save the 700 bucks and buy more parts. However, a tune will ensure the engine is running properly AND add some more power.