Replace or reuse old exhaust manifold studs?

Should these studs be cleaned and reused, or replaced? If replaced, which do you guys recommend?

I replaced Warbirds with the kit from Bill at Mazda Roadster, this one to be exact: http://www.miataroadster.com/miataro.../i-412315.aspx

You could step up to the ARP ss studs but at twice the cost I personally couldn't justify the cost beyond the standard kit. Very happy with the kit I used and will probably get another one for Misfire if I remove the exhaust manifold and can afford the added expense at that time. :D