the fosgate can be used but the box has to be taller. This can cause problems with the tie down points on the sides.
If you are not a pioneer or MB Quart fan, there is the alpine type R, clarion makes a sub that will fit.
Any sub 3.125" deep or less can fit.
as far as amps, there are a lot that fit, and I have made custom racks to fit special amps upon request
I agree on the bad return on investment. FOr the cost of the pioneer TS-SW2501 or MB Quart RPL254, and so many people are using them and are happy, its hard to recommend any other subs. None are as proven as these ones in this box
What u guys think of the pioneer gm-d7500m to power a pioneer ts-sw2501s2?