I just bought a new 2011 audi a5, with the bang and olufsen sound package. What i was wondering was if it is a better idea to take out the current sub (by the rear window) and replace it with a 10 inch sub like a jl, or just do a trunk setup. The only problem i see with replacing it, is it is not sealed so itd be a free air, does jl even make free airs anymore? The other question is what would be a good sub, i want something powerful (i really like the w7) but i dont want to destroy my new car through the vibrations, especially the trunk. Also, would it overpower the B&O system? The other thing is i want to still have a lot of trunk space, would it be possible to mount a thin line sub in the side, like where the nav electronics are hidden?

This is what I did:

http://forums.audiworld.com/showthread.php?t=2794390

QW's method would certainly be an improvement.

JL does not make an Infinite Baffle subwoofer any more. You'll want to find a sub with low Fs, high Qts, and alot of xmax. I've been exploring all the options over the past several months, and I've found that I would have to special order what I want. There are really no true IB subs in 10"--the ones out there are compromises. My only concern here is mounting depth and speaker diameter--in other words, will I be able to clear the rear window with such a substantial speaker?

A few days ago I posted a link to a fiberglass enclosure for the driver's side trunk pocket.

Another option is using a prefab enclosure or having one built.

Thank you both, QW i like the idea of your setup, would it be possible to do something like that with say a 10w7, and just have a small box to seal the sub, my only concern would be would it have any problems because its firing directly up towards the window?

I posted this;

http://forums.audiworld.com/showpost.php?p=24059923&postcount=74

Which is part of this extensive thread on sub installs. Both the JL & Kicker subs have been used in IB mode with success. The JL Audio 10W1V2-8is probably easier, but the 10" 8 ohm Kicker Comp sub is approved for IB installs and works fine also.

http://forums.audiworld.com/showthread.php?t=2790664&highlight=B%26amp%3BO+Subwoofer+Upgrade+Install+Gu ide