Radioshack Pro Series vol req

I don't even want to hear about the fact that they are radioshack speakers (I already know)

I just need to know what you opinion is of how much volume i should have in a seald box for them? 1 12" per box

These are in my home stereo speakers that are an old brand and i had to replace the woofers, they are an old 4 Ohm set and since i worked at radioshack i got a fat discount and bought them on sale.

I have recently realized that the size of the orriginal box may not match the requirements of the subs, so i decided to look into it.

Also, I'm mostly worried about the orriginal boxes being too big, they also hold a mid and tweet, What should i use to fill the space if need be?

Thanks

sounds good

any suggestions for the enclosure volume?