01-05 Lexus IS250 Aluminum Exhaust Header Gasket

Do I need to replace the bolts or use thread sealant when installing this?

The gasket alone handles the seal—use your factory bolts torqued to spec. Thread sealant is not required, but you can apply it if running a modified boost setup for extra security.

Can I reuse the old header bolts, or should I buy new ones?

Reuse is fine if bolts are clean and threads are intact. If you've spun the fasteners during removal or they show corrosion, grab new hardware—cheap insurance against a leak down the road.

What prep do I need before installation?

Clean both mating surfaces with a wire brush or gasket scraper to remove old material and carbon buildup. Surfaces don't need to be perfect, but they should be dry and free of loose debris.