Well, mine's the S6 Neo, but principles are the same.
Hard wiring was just a case of running the power from near the radio, up behind the speedo area and out by the A-pillar, which is where the screen is mounted.
You can then run the cable to the radar detector up around the windscreen, tucking it in the lining, and mount the detector behind the rear view mirror.
Very tidy and easy. Hopefully, the B2 is the same.
I put my S6 at the junction of RH dash and A-pillar, as it is in line of sight, doesn't obscure any instruments, is slightly hidden from external view by parking permit pouch etc, AND, I believe there has to be some distance betwixt detector and screen.