I know that some of you have been putting in 5.25 in the back of extended cabs, but do you think it would be possible to put in a 6 1/2? The reason I am asking is because I bought some kicker 6 1/2 for the front and 5 1/4 for the rear, but they sent 2 sets of 6 1/2. So I'm trying to decide to either send them back or keep them.