This is a request by e-mail for two Orion HCCA 12" subwoofers and a blowthrough in an F250.

Has a very high sensitivity and still has good output down to 30hz. Passband is 30-60hz.

As a small design example:

Design can be found here: 2xHCCAs Series-tuned 6th order blowthrough - $30.00 : TheBoxHouse, Enclosure designs

Wish I could be there to hear this one!