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

Inspect your existing header bolts when you remove the old gasket. If they're in good shape with no stripped threads or corrosion, reuse them. If they're rough or corroded, swap them for new ones while you're in there — it's cheap insurance against a leak coming back.

Should I clean the header and cylinder head surfaces before installing this gasket?

Yes. Use a gasket scraper or plastic brush to remove all old gasket material and carbon buildup from both the header flange and the head. A clean metal-to-metal surface is what seals; debris trapped under the gasket will cause exhaust leaks.

Is there a specific torque spec I should follow when tightening the header bolts?

Refer to your vehicle's service manual for the correct fastener torque sequence and spec. Over-tightening aluminum gaskets can cause warping; under-tightening leads to leaks. The manual walks you through both.