My problem is i bought some alpine sps-600 speakers and there 6 1/2 in.
Apparently the rears are 6 3/4 and i cant get mine to fit. Is there something I'm doing wrong or am i just not installing it the correct way?

 

install them from the bottom and use short metal screws

 

Get adapters.

 

hatch or coupe?

Coupe, you can make an adapter plate for smaller speakers in larger holes. For the speakers I suggest, using foam baffles to obtain clearer sound.

Also, if you decide you want to put a sub in the rear deck, you can cut the hole between the speakers for a 10" sub. Remove the rear deck lid springs that run under the rear deck, make a box that follows the rear deck from under, seal it and bolt it in. As you will now have an issue opening the trunk, go to your local yard and pull the hatch struts from a bubble style civic "i think those where the ones we use" and enjoy.

Side note, if you have a wingless deck lid, expect the deck to fly open when the trunk lever is pulled.

Hatch, it's a lot easier, you can take the plastic adapters out and throw them as far as humanly possible. cut to fit what ever size you need and again use foam speaker baffles under the speaker.

I know it might sound like a lot or ruff in understanding, I would post picks but I can't find the pics from ones I have done in the past.