I underpower about everything I run. It will not hurt them. What blows the subs with a small amp is clipping. The gain is turned up to high sending a distorted signal to the subs. The amp is running out of power which damages subs and will eventually shorten the life of the amp. Whatever you do build your own box, have a local member do it or something. It is not complicated at all. Just make a sealed box. Start a thread and folks will design one for you with the measurements of your car. Take the list to lowes if you don't own a saw. They charge a fee to cut I think.
Years ago if you wanted sq you went with 8s. If you wanted sql you gave up a little sq for volume. 8s could bounce back quick, 10s a hair slower. 12s were kind of dogs until the pioneer impp came out. Today if you hear 10's are for sq it is hogwash. That 15 misfit recomended will outdo a lot of subs out there plus have more spl. Personally I still run a lot of 10s because I want low spl. But today there are 18 and 21 inch subs for sq that are as accurate as the 10s I run. For the name game check out those listed along with eclipse, sundown, titanic mkIV, shiva, ed, diamond and used brahmas to list a few. You are not going to get a lot JL sugestions due to the price vs. product. For a sql setup with huge bass and a sub that can handle the bpm of metal a W7 is hard to beat. I would still go with the incriminator misfit suggested though. w3 are not in the same category as the rest that folks have suggested. And they are better than the others you listed.
