Of course, these subs will require some cutting of the rear deck (and some extra bracing/stiffening bars), but with a mounting ring above the deck, it should fit in just fine, and be able to use the stock grills (again, with modifications). That steel bulkhead behind the rear seat should really help with sealing off the trunk space from the passenger space.
I measured a 6.5" factory hole in the rear deck(someone else stated 6.75"). You have slightly less than 3" of depth due to the gas tank bracket clearance. Without cutting, your choices are very limited.
I'll be interested to see how your rear deck mounted ODws work out. I didn't want to go that route. Btw, nice choice of subs . The OD series components and coaxs are pretty awesome sounding also. Good luck.
Using the stock plastic speaker ring, it will hold a speaker size of 6.75. (6 3/4)
Anything less that 3" mounting depth (using the stock mounts) and you should be ok, as the trim ring adds about 1/8th inch. There is plenty of room to go up inside the stock bracket via a spacer though.
iqbalinc got his 8's in via some heavy modding. See his link here.