I recently completed my 2010 3 hatch, and according to forums (amazingly not this one, but two others) you NEED 1" risers for the front (when using 6.5s)... NOT the case. 1/4" did fine for me. depending on the size of the 6.5s magnet diameter would be the most likely concern. I didnt take measurements, but did take plenty of pictures... and for the back the adapters alone work, and you have plenty of room.
what I needed
4 SA68 plates
2 1/4" spacers for 6.5s (had them from previous install)
dampening (kill any possibility of adapter/spacer plate vibrations)
also.......fyi: gj6a-68-ab1 is the mazda part# for the door clips, its not if you break them, its for when you break them
and the speakers should go in fine.
WINDOWS DOWN WHEN YOU INSTALL SO YOU CAN BE POSITIVE
not too deep, still 3/16" gap to window/metal on side
you will lose stock tweeters unless you jump the lefts and rights of the mazda 4pin together when splicing for the aftermarket speakers from the center... not getting any more into wiring here... maybe a howto in a few days/weeks/months...