I just checked out the MB Quart PCE 216 components and they sound
AMAZING. I'm thinking about putting them up in the front, but I'm not
sure if they're going to fit; they're 6 3/4". Would I be able to get them
in with a little help from a Dremel?

Wow took me a while to find the mounting depth. MB Quart site is somewhat lacking ... grrrr. Any how Crutchfield lists a top mount depth of 2.5" and a cutout of 5.635". This means you will have to cut the basket but you should clear the metal cross beam immediately behind the basket just fine. I crammed a CDT Audio CL61 with a top mount depth of 2.875" and a cutout of 5.6875". You may need to rotate the speaker to have your posts not touch the cross member.

that's great... thanks silk!