an hfi like recommended already has a 5.5 mount depth for a 12" and doesnt need back spacing it is perimeter vented //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
an RLP304 mbquart is about 100$ and only needs .5-.75 sealed for a 12" //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
and btw it has a 3" mounting depth //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif