I want to install my ported exhaust mani and o2 housing. I have a new exhaust manifold gasket and the gasket for the o2 housing, do I need any others? I am curious about the gasket for the downpipe, will that HAVE to be replaced as well as the gasket to install a test pipe in place of my hfc???

 

You should replace the gaskets on the exhaust if they are brittle and cracking. The "doughnut" gasket that joins the O2 housing and downpipe can be reused. I have yet to replace mine in all 4 years of owning the car, still no leaks.

 

So I guess I have all the gasket at least for the o2 housing and exhaust mani swap???

 

Yes