EG 4-door system install questions

[Leets]

Hopefully someone can accurately help me out. I put a pioneer deck in my 4-door (soon to be swapped out, but still) and there's still a bit of room in there. It's a single din and all, but I can't seem to get the bracket that came with the system in there. Seems the bracket's too big, but the system is too small. Is there some sort of special bracket I need to securely mount an aftermarket system in there? Also, everyone I've talked to and everywhere I look tells me that the 4-door civic uses 6.5" speakers. If so, then I must have one ultra rare Honda, cuz mine doesn't. I know what I'm talking about here, just trust me on this one. Anywayz, I've already put a set of 5 1/4" in the front (fit perfectly in the stock bracket), but it's the rear I'm concerned about. There's no bracket and the factory units just had a three bolt mounting. What do I need to get/do to put in some 6.5"? Thanks.