I would either stick with the stock driver, or build/upgrade to a newer sub. Reasons being:
1. When companies design subs their amps usually have a built in form of protection (called a highpass) specifically for the stock driver in that given alignment.
2. The enclosure volume is also considered to be the best compromise between size/performance possible for that given situation.
would you at all be interested in building a DIY sub? Why mess with the HSU if it works so well?
