Can you please explain in detail what you did?
I removed the subwoofer box from the truck, and seperated the speaker from the box. Then, I borrowed a bag of poly-fill from my wife, similar to this
. I inserted about 1/3 to 1/2 of the contents into the box around and behind the speaker, and re-installed everything in reverse as I removed it.
I'm in no way an automotive audio expert, but folks in that space have been doing this for years to make a box "seem bigger". If you Google polyfill and subwoofer, you'll find numerous hits explaining the physics behind the effect.
More power and a better speaker, this does not trump. Though for a minimal time investment and very little cash, it's a reasonable upgrade, imo. I would say I can feel the bass slightly more. You may be able to play with the amount of stuffing to have a more, or less, dramatic affect- good luck!
If you try it, please tell us what you think!