Salvaging Polk RT2000

[Dave Jones]

I have a set of home theater speakers I bought before my enlightenment. The mains are Polk RT2000p's. Just for the halibut, the other day I dug into them. I was pleasantly surprised with the solidity of the cabinet. So I am wondering if they might be salvageable by replacing the drivers and crossovers. To keep costs down, I would want to keep the built-in amp, and of course I have no idea what kind of EQ it might have. I would need to test it before proceeding. But what I am wondering is if it is even possible to get good bass response from the cabinet.

It uses two bass drivers, of about 7 1/2". The bass cavity is about 2.2 cubic feet. There is a down-firing port, 4" in diameter and 8" long.

Is there even such a thing as a bass driver such that a pair of them would work in that box with that port?