That's a different FMIC design. The standard battery won't fit with the Apex FMIC. Even with the smaller battery I mentioned above, it has to be fitted at 90 degrees.
If you're fitting the Apex kit, I'll be very surprised if you don't have to trim the bumper...
I won't put my battery in the boot. Apart from it being a complete ball ache running the cables, it will also ut extra strain on the battery running the current the entire length of the car. Particularly the turn-over current...