I called ahmotor to inquire about exhaust manifold gaskets. I told him I want to install aftermarket headers and he told me that I can not use oem ones, is this true?

I need all three peices: the 4 ring, 2 ring and the 1 ring since it's a 4-2-1 header

 

The exhaust manifold gasket has to be the same, because the holes & bolt pattern on your head don't change.

The gasket at the cat has to be the same, because it has to fit up against the cat.

The gasket in between the 2 parts of the aftermarket header don't have to be the same, but don't they come with the header? I got a DC 4-2-1 header for my '95 GS-R, and it came with the 2 metal O-rings for that. But they WERE the same size as the OE (GS-R) O-rings. Don't know about other brands of headers...

 

i have neuspeed n2, they're knock off of dc headers

you have a gsr or ls?