Do I need new gaskets or bolts to install this?

You'll want fresh header gaskets since removing the stock header breaks the original seal. Bolts typically reuse if they're in good shape, but new hardware is cheap insurance for a clean install.

Will this need any prep work before bolting on?

The header comes ready to install. Check that mounting surfaces on the engine are clean before you bolt it down—no sanding or priming needed on your end.

Can I still use my stock exhaust system downstream?

Yes. This header uses the same outlet diameter as stock, so your exhaust piping, muffler, and resonator all bolt up without modification.