Do I need new fasteners to install this gasket?

The header bolts typically stay in place — you're only replacing the gasket between them. Check your bolts for damage before reinstalling; if they look worn or won't tighten down evenly, swap them out at the same time.

Should I clean the header sealing surface before installation?

Yes. Remove all old gasket material and carbon from both the header and cylinder head with a gasket scraper. A clean, flat surface is what stops exhaust leaks — don't skip this step.

What should I tighten the header bolts to?

Refer to your vehicle service manual for torque specs and tightening sequence. Uneven tension or wrong torque will cause gasket failure and exhaust leaks.