high sensitivity Subwoofer

so i am looking to add a couple of sub-woofers to a custom van, they will sit in the back and i would like them to be 14 inch or bigger but not past the 28 inch mark unless there is a 28 inch or plus which is better than two smaller ones, anyway i don't want high power handling i would prefer high sensitivity so it takes up less power, if anyone could tell me where to look or suggest me a couple of drivers and maybe a 12v amplifier to go with it
many thanks to anyone who helps