seal components or not

I have the Alpine Spx 177A  6.5 components I was wondering what would be the best thing to enclose them in.

1) factory location in door with back open.

2)Sealed fiberglass enclosures. 

I thought to get any kind of midbass I would need to put them in sealed enclosures but I came across some people that said components are not ment to be in sealed enclosures.

I already have two layers of b-quite extreme on my front doors but after looking at the stock location the back of the speakers would be open to the whole door which is not really sealed since there is that slot the window goes up through.  So I built fiberglass speaker pods for them but the midbass sounds a little too tight alomst like the enclosure is too small.  I wanted to redo them to try to get them close to the internal volume suggested in the manuale  plus I want to make them fit in the car a little nicer and not stick out so much.  This was my first time using fiberglass I think if I redo them they will come out a lot  better.

http://www.nissanclub.com/forums/vbgarage.php?do=getimage&id=1225

I came across this article in car audio magazine this guy used the same components that i have and sealed them in a .33 cuft enclosure so i was thinking of going by that internal volume.

http://www.caraudiomag.com/v_features/0109cae_bmw/