With these 6inch speakers can I use the stock old speaker as a spacer or do I need to get 6 1/2 inch speakers to do that?

I'm only running these 2 speakers in the car; simply, b/c I can't stand those speakers blaring behind my head. So if anyone has any recomendations for what amp to use that would be great.

I orignally wanted a d6 sub as well. More than likely just a 10 inch. Is there an amp that could run all three speakers?

Thanks in advance, - Mitch