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

Not necessarily. If your existing bolts are in good condition and torque down evenly, they're fine to reuse. Inspect them for corrosion or stripped threads before reinstallation.

Should I use gasket sealer or adhesive with this?

Aluminum gaskets typically work dry at the header interface. Apply a light coat of high-temp gasket sealant if you're seeing micro-leaks after torquing, but this gasket is designed to seal without it under normal conditions.

What torque spec should I use when bolting the header back down?

Refer to your vehicle's service manual for the correct fastener torque. Tighten in a cross pattern to ensure even clamping pressure across the gasket.