proper core for a v-mount

What is the proper core for a V-mount setup (size)

here some pictures

http://i61.photobucket.com/albums/h71/lsupremealbum/25x14x4.jpg

25x14x4

http://i61.photobucket.com/albums/h71/lsupremealbum/l_b220126bee7af74ecac38a608d634c77.jpg
http://i61.photobucket.com/albums/h71/lsupremealbum/l_b1028ce78c345e9438ba19bf22a337b4.jpg

http://i61.photobucket.com/albums/h71/lsupremealbum/24x12x3.5.jpg
24x12x3.5

http://i61.photobucket.com/albums/h71/lsupremealbum/garagenankin2002-img600x450-1173434.jpg

http://i61.photobucket.com/albums/h71/lsupremealbum/david1importintelligence.jpg

http://i61.photobucket.com/albums/h71/lsupremealbum/DSCF1510.jpg

http://i61.photobucket.com/albums/h71/lsupremealbum/DD9EUFSKNULG8HG.jpg
http://i61.photobucket.com/albums/h71/lsupremealbum/WAW5VFXKO9217G8.jpg

dont need something hudge 2.5 or 3 is ok ,dont plan to go higher than 350 hp
at least not for awhile.
i want good airflow and a core that would let my battery where it is(if possible)
what you guys think ??? Best core that will do the job properly