If you're going to change the gasket use some high temp copper RTV on it. You'll get a much better seal.
When you do it clean both sides of the flanges, smear it on both sides of the gasket, give it 15 minutes, put it on, put on the headers and intake, snug everything but don't torque it down yet, then wait until the next morning to torque down the nuts on your studs. This will ensure a good seal.
I had a heck of a time getting mine to seal until I heeded the advice of my elders here and used the RTV.
Good tip. No leaks on my integrated exhaust manifold, so i don't need it until I swap the whole top end at once. All at once kind of thing.
