Alis are great subs. Hugo's got a 10 in his Beetle. They're very definitely not the best choice if all you're looking for is sheer power, but for sound quality, they're one of the best options out there. The 8s are, as you say, not so much a sub, and more of a mid-bass driver, so I think you'd probably be better off with a 10, but with them being so slim, getting one into the passenger's footwell shouldn't be too difficult.

Dominic

Cambridge Car Audio
http://www.cambscaraudio.co.uk