So I think one of my stock subs is starting to go, so I want to replace them both.  I want to keep them in the factory position.  I've seen two different sizes for those subs, either 6x9 or 6.5.  Which is it?  If I went with 6.5 subs, will they fit in the hole if the subs are actually 6x9?  I need the trunk room, so I don't want to go with an enclosure.  Any suggestions?