Do I need new hardware to install this gasket?

Hardware not specified in the product listing. Reuse your existing OEM header bolts unless they're stripped or damaged—most installs don't require new fasteners.

Should I clean or prep the gasket surface before bolting it down?

Yes. Wipe both the manifold and header mating surfaces clean with a rag to remove carbon buildup and debris. Any gunk left behind will create a weak seal.

Is this a single gasket or a set?

Single gasket per order. If your vehicle has dual headers or you're doing both sides of an exhaust system, order two.