What i did to the factory enclosures that helped the sound alot in my opinion was put some dynamatt inside covering the area were the back bracket leaks air. It made them more airtight and got rid of some resonanse. Then i put in some speaker baffling and sealed up the lip of the encloser were the speaker mounts into, air leaked there as well.. Finally put a small removable rubber plug in drain hole again making encloser more air tight but easily removed for drainage if needed.
Definately not an amplified tower spkr setup but made factory system better. I only used factory enclosures as they look factory. I put my own head unit in instead of jensen unit as i had a spare unit and its got no seperate amp its in the head unit itself. Its a boat radio called millenia from prospecelectronics.com they are very economical basically fit were factory head unit goes and have about the same output as factory.