Exhaust questions

[t.mcginley.jr]

Hi guys, I just got a 1990 300zx NA auto with 98k miles on it.

The PO told me that both exhaust headers are leaking at the gaskets so I will probably need to pull the engine to replace those gaskets and while it's out do some other work.

I've read up about the exhaust systems on the NA's and want to see if this idea will work. I want to get some aftermarket headers, nothing fancy and a catback exhaust. I understand this part, but my question is about the cat converter section of the exhaust (pieces between manifolds and stock H pipe). Assuming the pipe itself is good, can I have an exhaust shop cut the stock cats off and put new high flow ones on?

I live in NJ so they're crazy about emissions so having cats is a must, but will the high flow ones give me any problems? And also, the O2 sensors on the car are on the exhaust manifolds correct?

[vulcanrush]

I live in NJ so they're crazy about emissions so having cats is a must, but will the high flow ones give me any problems? And also, the O2 sensors on the car are on the exhaust manifolds correct?

the O2 sensors, i think they should be on your stock precats?

[240obsessed]

I live in NJ so they're crazy about emissions so having cats is a must, but will the high flow ones give me any problems? And also, the O2 sensors on the car are on the exhaust manifolds correct?

the O2 sensors, i think they should be on your stock precats?

He has an NA, so no precats.

And OP, yeah I'm pretty sure those O2 sensors are on the exhaust manifolds. I also don't think high flows will give you any issues.

[t.mcginley.jr]

Thanks for the replies

Yeah I've figured out that on the NA's the O2 sensors are on the exhaust manifolds, one on either side. Now I'm just trying to decide which catback to get. I want a 2.25" one

[vulcanrush]

He has an NA, so no precats.

And OP, yeah I'm pretty sure those O2 sensors are on the exhaust manifolds. I also don't think high flows will give you any issues.

if you have an na, you don't have exhaust manifolds either, correct?

[mrmoose]

FYI you dont have to pull the engine to do the exhaust gaskets on a na. i just did a guys whole exhaust system, and if you are going after market it will be even easier. the hardest part is getting around the heat shield to re-tighten a few bolts..

[t.mcginley.jr]

NA's do have exhaust manifolds. They look like headers wrapped in a heat shield with an O2 sensor bung on each collector.

And that sounds like a PITA to replace the gaskets with the engine in still. How long did it take you? I want to do a few other things like injectors, egr delete, valve cover gaskets, etc. It will take me less time to everything with the engine out then to bust my a** trying to work around the engine bay.