Hi new to the forum…
I bought some bolt on after market cats..
the flanges are to small bolt on pattern is off.
Am I ordering the wrong cats… anyone else have any ideas what’s wrong

 

Pics might help, but it sounds like the wrong ones. Or it could be as simple as flipping them around or switching sides.

 

You can’t turn them around

 

i am pretty sure the header flanges de to hr are different

 

Thank you so much… been scouring the web trying to figure it out..

 

They are. Probably would have been a better question to ask where you ordered them from and what year Z you have.

 

It’s a 2007 and I got them from exhaust distribution.. the title says base model.. but I was told it has nismo exhaust

 

Pics of exhaust

 

I don’t have pictures of the exhaust right now only cats..

 

You need to make sure you get the VQ35HR compatible cats. The 3-bolt flanges that mate with the exhaust manifolds are different between the DE and HR. The pictures you uploaded are showing the DE version.
Good Luck!
-Icer

 

Thank you all.

 

Also, the 3 bolt flange uses a donut gasket, not that flat thing. Get new gaskets from the dealer. If the aftermarket cats you got don't use the factory style gaskets, you got cheap Chinese cats. Send them back and get proper ones.

 

So I sent back the other cats and now waiting on the new ones. So another question. If the cats have to be for an HR motor does the 02 sensors have to be as well.

 

Yes, all four are different between HR and DE. But why does it matter of you’re installing the correct cats and can reuse your existing four sensors?

 

Because I bought new 02 sensors when I bought the other cats and had them switched out but they are throwing a code..

 

Got it. Sadly non-compatible.