I know exactly what you mean. I have a 15" eclipse titanium tuned at 28 hz and it gets the killer lows but the 2 12" Boston g5's sealed I have in the gp just sound so good. I'm not sure what I'm willing to sacrifice at this point, the low lows or the sq. I'm wanting the 8's for partly the same reason, but the other reason is that given their sensitivity and power rating, they should almost be twice as loud as the 6.5's. I've been considering trying to make their recommended ported enclosure into the door. Although if anything they will at least be in a sealed enclosure. I think with what you've got on the door panel, getting an 8" grill may be easy to mod the door panel with. Then just cutting out several mdf spacers to set the speaker out from the door, should work fine. What do you have for tweets?