The headpipe gasket seals the joint between the head pipe and Exhaust port. These gaskets are designed to crush a little bit to tightly seal where the pipe fits to the head, thereby making them a single use part. Get a fresh one now avoid having an exhaust leak when you install your new exhaust.
The muffler joint gasket seals the joint between the head pipe and muffler. These gaskets are easily damaged when removing the original muffler. FMF mufflers (Q4 or PowerCore 4) do not require a joint gasket but the all other aftermarket mufflers as well as the stock muffler do require a joint gasket. Get a fresh one now to ease installation of your new performance muffler.