The 34" Audiobahn is totally impratical for car audio. The install pictured above does not even come close to meeting the requirements for a reasonable enclosure alignment (ie: not getting the low end or output the sub is capable of in the right box). Not to mention, they are huge, but their excursion capability is lackluster. A few smaller subs could easily out-perform it. It is interesting for a radical home audio substage however, as its pretty efficient iirc (given is cone area heh).
I have a pair of RE XXX 15's and a high efficiency ImageDynamics/Audax 3-way horn front stage powered by class A amplifiers (currently still installing). It should wang.