On my rear 6x9 infinites, they have the adjustable directional tweeters (2-way), but which way to face the would sound the best? I've always had both facing towards the outside, but I'm not sure anymore if thats the best setup...

 

Why don't you try them each way and decide which sounds better to you, then leave them that way?

I am just guessing, but I would think that either way, they would mostly bounce off the rear window toward the front.