So I purchased a 2002 Audi A4 3.0 quattro with Bose symphony audio in January and I love it. However within 2 weeks I had new speakers and a head unit installed, due to the others being full of static and pretty much just beat. I believe the speakers were infinity reference's and the head unit was a pioneer 50w-4 mosfet. I didn't buy an amplifier or sub woofer due to their added cost. However while playing music I opened my trunk to grab a bag, and noticed the factory sub woofer banging away in the top of my trunk. The other stock speakers that I had removed were trashed and I assume that this one is too. Would I be able to buy and aftermarket sub woofer to replace the current one? Or would that require to much power from the factory amp? Would the diffrence even be substantial? Also, what size is the sub woofer and is it a shallow mount? Basically, what can I do to improve my cars bass without spending a lot of money? I would prefer to use the metal lining in the top of the trunk for the sub's enclosure since it is already there. Any help is appreciated, thank you.

 

I am not 100% certain but I believe the kicker shallow mount will fit in the factory location and will work without an additional amp.

 

OK, I was looking at a kicker shallow in particular. I'm going to get it checked out by a car audio specialist beofore I buy anything but thank you very much for the reply.