Do I need to replace the header bolts when I install this gasket?

Gasket alone is all that's required — reuse your existing header bolts. If bolts are damaged or stripped during removal, you'll need replacements, but they're not included here.

Should I use gasket sealer or RTV with this?

Test-fit first without sealant to confirm alignment. Many builders apply a thin bead of high-temp RTV around the gasket perimeter for extra insurance against micro-leaks, but it's not mandatory for this gasket type.

What's the return window if the gasket doesn't seal?

Contact ModSupply customer service with photos of the leak point and installation details — they'll walk you through diagnostics and handle returns if the gasket is confirmed defective.