Sometime in the near future I'd like to buy a Gibson Explorer. This is probably a dumb question but I don't really know much about the pickups on it. Are they better or worse than my set of seymour duncan black outs?
The 500T is really hot, and the 496R is a bit more smooth, little less output. Both are ceramic magnets, I believe.

They're passive, so they'll sound quite a bit different than your Blackouts.
It depends on what model of Explorer you're talking about. Also there is no such thing as "better" and "worse" with pickups, just "different". Plus SD Blackouts are active pickups and most guitars, probably including this Explorer, come with passive pickups. So that's quite a difference there. Don't forget too that pickups are only a small part of your guitar's sound, especially in the case of a set neck, heavy-bodied guitar like an Explorer the build of the guitar itself effects your tone more than a specific model of humbucker does.

Basically yes there probably will be quite a difference but that doens't mean it'll be any better or worse, more things effect your tone than just your pickups and if anyone is going to comment on the sound of the pickups then you need to specifiy which particular Explorer you're talking about.
I'm not sure, I guess the generic current model?

I would figure I'd keep them in since they're made for that guitar. I usually deal with cheaper guitars where changing out the factory pick ups is a must
What do you play? The stock pickups should handle any high-gain fairly well. I think the 500T is like 13k or 15k...
Yeah the basic Gibson USA Explorer has the 496R and 500T. The 500T is pretty much the same as a SD Distortion, a little thinner-sounding than a DiMarzio Super Distortion. It will do metal fine though the sound won't be as detailed as the active Blackouts you're used to. The 496R is kind of crap, just as most ceramic neck pickups are. It's almost the same output as the 500T which is just silly to have in the neck. Muddy and unresponsive. You'll want to change that for a bright alnico-based pickup to get closer to the sound of the Blackouts.