My whole deal with a "close" to direct replacement was
1. Fairly simple to install
2. Didn't take up any extra room, in a TJ loaded with spare parts and camping gear this is pretty important...well actually just in a TJ. This is very important
3. I was also concerned that a larger woofer might overpower the rest of the system? Then I would have to spend more money than I ever wanted to on a well rounded system.