Do I need new header bolts when I install this?

Header bolts can be reused if they're in good condition and torque down smoothly. Inspect them for corrosion or stripped threads before reinstalling. If any bolt feels loose or damaged, replace the set.

Should I use sealant or anti-seize on the gasket?

Keep the gasket dry — no sealant needed. Torque the header bolts to spec in a cross pattern for an even clamp load. Anti-seize on the bolt threads is fine, just keep it off the gasket face itself.

What if I reuse the old header bolts and it still leaks?

Return it within 30 days for a full refund if the gasket fails under normal install conditions. Most leaks come from under-torqued bolts or warped headers — confirm both before assuming the gasket is faulty.