I would be careful with that amp/sub combo.
Power handling for the sub is listed at 200watts RMS at 4ohm, 400watts peak at 4ohm
The amp is listed as mono 1000watts at 4ohm. As it doesn't explicitly state, we can assume this means peak and not RMS. So assume about half that will be RMS, so 500watts RMS at 4ohm. This is a full 100watts higher than maximum for the peak power handling of the amp. Pump it a little too high and consider your sub blown. Try and find a sub and amp that have better matched power handling: that is the RMS power of the amp matches that of the sub.
Furthermore, in a smaller car like an X3 a sealed sub makes the most sense.