I'm not really a fan of the ceramic headers. I'm not sure why everyone calls them ceramic, seeing as they're made out of mild steel and have a ceramic coating. They can still rust pretty easily.

Also the skunk2 exhaust is pretty freakin loud, but I guess if you're interested in canister style exhausts then that's what you're going for.

If you really can afford only one thing for the time being I would go for the exhaust since even if you upgrade the header it will be flowing through the restrictive stock exhaust and not make much power.

That said, a really loud exhaust like the skunk2 on a car that's making close-to-stock power is kind of pointless since the noise is only there for its own sake rather than to make more power than a quieter exhaust.