I read the stock bose sub is a 9" woofer. Can I swap it with a JL Audio 8W0-4, its a 8" sub with a overall diameter of 8.54 in, http://mobile.jlaudio.com/products_s...p?series_id=22

 

Yeah, if you remove it and look on the label, it says 9". Leave it to those Bose bastards to make it a size in between NORMAL size subs. I'd suggest bring it to a professional shop and get it cut a little bit more and slip in a JL 10"w3v2. I have 3 of those in a box in my trunk and they are beyond powerful. I was thinking of doing the same thing. Right now, I have that sub removed and theres just a big hole there, allowing bass from the trunk, into the rest of the car.
Personally though, i'd stay away from the W0....

 

"Can I swap it ..." If you mean remove the stock sub and put the new jbl sub on the same location, that would be NO !!! This is because there is a retention bar just below the stock sub which blocks any sub that is taller than 2.25". There are a few shallow mount subs out there in the market and some of them support free air but the base won't hit as hard as a sub in a box. If you like a loud base, I would go with a sub in a box.

Just my $0.02.

 

The bar can be removed or even cut, or if you wanna get technical, even altered and lowered. You can then bolt the sub in a box and then bolt the box into the top with the sub in the car. A simple bar is not a problem.

It's just going to be a tad bit more confusing.