I'm upgrading the exhaust on my car and going with MAC performance y-pipe for stock manifolds. The local parts store lists flange gasket for my car but then I read other posts say it doesnt have any and use sealant and then again yes only one on the drivers side. Do I need none, one or two, whats the scoop on this?
http://www.summitracing.com/parts/wl...make/chevrolet

I didn't get any input on this. I went ahead bought both donut gaskets. I'm having my exhaust worked on today. I'll post back to let the next guy know what's needed.

you need one flange(donut) gasket.

So the driver's side is the run-of-the-mill flat gasket and the passenger side the doughnut gasket, is that it?

The stock manifolds have a flange cast into driver's side manifold outlet. The passenger's side manifold outlet is flat, because it was originally designed to mate up with an exhaust flapper casting. Later cars don't have the flapper, instead they have a cast iron spacer to make up the difference. The spacer doesn't exist in the aftermarket. A creative individual can make it work with an exhaust donut, but the donut doesn't match up and fit anywhere close to as well as the GM spacer.

Cool. Thanks for the answer. I am changing the exhaust manifold gasket so I am not touching -nor apparently need to touch- the pipe2manifold connection then, correct?

GM didn't use gaskets with the stock manifolds. If there are gaskets there, someone added them. Assuming stock manifolds, make sure both surfaces are true, flat, and clean, and torque them to spec. As long as the surfaces aren't pitted, or damaged, they should seal without gaskets. Most of the corny exhaust gaskets will just burn or blow out.

Now headers on the other hand may need a gasket, but if then have a thick mounting flange, I'd consider having them machined flat, and again skipping the gaskets.

Thank you again. I did the headers last year after blowing the gasket and used new gaskets since the handbook schematics had them and the gasket set came with them. But back to my predicament: If no gaskets on the stock pipe-to-manifold connection, technically, there shouldn't be a problem since there is nothing to blow out: Hopefully, I can get away with simply replacing the exhaust manifold gaskets without dismantling the pipe-to-manifold connection: Do you think it is possible to leave that pipe-to-manifold in place and connected, and still effectively replace the exhaust manifold gasket(s)?

Not sure if this is beneficial to this situation or anyone having a similar issue of connecting a y-pipe such as Magnaflow to stock TPI exhaust manifolds there is an exhaust flange gasket at Autozone that looks to fit perfectly. It's from Walker, p/n 31533. The inner diameter aligns perfectly with the TPI passenger side manifold. It is not the same thickness as the original spacer, but it might do the job in a pinch.