Do I need to replace the gasket every time I pull the header off?

Aluminum gaskets can be reused if they're not crushed or warped. Inspect it after removal—if it's still flat and the seal surface is clean, you can reuse it. If it's compressed or damaged, replace it.

Will this work with a stock header or only aftermarket ones?

Designed for factory header fitment on your generation Miata. If you're running an aftermarket header, verify the port layout matches before ordering.

Do I need any special sealant or prep before installing?

Clean both the header flange and cylinder head surface with a wire brush to remove carbon and old gasket material. Most builders use a thin layer of high-temp gasket sealer—check your header or engine manual for the specific product recommendation.