I think I'm finally down to the last little bits of the setup for my
99 BMW 3 series convertible. The last pieces are the head unit (I'm
thinking Alpine CDA-9835) and the sub.

Unfortunately, there's no way that I can put the sub in a box at the
back of the trunk, Eddie Runner's advice not withstanding
(http://installer.com/tech/aiming.html). The only choices are a pair
of ten inch subs tucked in the space below where the convertible top
hides when it's down or a single 12 inch sub in the spare tire
compartment.

I'm thinking about going with JL audio for the sub(s) and the amp will
be a Brax X2000 that I can bridge into 4 ohms to 750 watts or 2 ohms
to 1115 watts. Another of the same amp will power CDT643 speakers in
pods in the kick panel and door.

This is purely a SQ install and I've heard it suggested that 10 inch
subs will have better sound that 12 inchers. I don't know if I buy it
and thought I'd ask here.

Thanks in advance!

Bob