Subwoofer for Volvo 940
 

Hi all,

My car is a Volvo 940 2.0L SW, few days ago I purchased a new radio receiver, a Pioneer AVH-3400NEX which is working fine.

Now, I want to change all the existing speakers (20 years old) and add a sub, the challenge is to preserve the loading space intact and use, possibly, either the under-trunk space or the spare tire.
Some pictures should help.

https://www.mediafire.com/convkey/26...a2klsxq64g.jpg
https://www.mediafire.com/convkey/bb...k84x7q9y4g.jpg
https://www.mediafire.com/convkey/24...5ets44wv4g.jpg
The space you see in the second picture right under the 4 screw holes which were holding my old CD Changer, it is 4" high, therefore I was thinking to a shallow mount sub in that position.

In the third picture you have the spare tire, however I still need to verify if I can fix it once it is flipped the other side, in that case I could use the https://www.pioneer-car.eu/eur/products/ts-wx610a or build an cylindrical enclosure a put a sub in it.
I do have deeper space on the sides (see first picture) but I would need elliptical woofers and there is not much on the market.

Do you see any other options?
Any suggestion is very welcome!

Alex