Hello all

I've just finished adding the Advent blind spot detection system to our 2023 countryman. This project is totally doable by a handy home mechanic, but not for the faint of heart. You do have to remove the rear bumper cover which is not all that difficult. Once it's off you have all the room you need to mount the radar sensors onto the plastic infrastructure beneath the tail lights, run the wires, etc. Advent gives you a handy angle gauge to make sure you're at 30 degrees; use a small spirit level to make certain you are vertical. You can install the control module in the left rear tail light access compartment and run the harness to the front left dash area under the carpet molding (quite easy to do). The system requires you to drill a 5/8 inch hole at the base of each windshield pillar. Just pull off the rubber door gasket and remove the clipped dash access panel. You don't have to remove the pillars; you'll have room to drill them resting the drill on the dashboard while pulling outward on the loosened pillar to see where the bit is going. Use a very sharp bit; the plastic material is very hard. There is plenty of room beneath and out of the way of the airbag. It's easy enough to snake the wire to the other side to access the passenger pillar and fuse box.

Word of advice: Once you're all powered up the system will give one long blink when you turn the car on. Multiple blinks are an error message and you have an issue. Test drive the car before reinstalling the bumper cover. You can temporarily install the tail lights without the bumper cover. You don't want to put everything back together and find there is a problem with the sensors only to have to do it again (like I did).

It took me two long shop days from start to finish but I saved about a grand in installation and I did a careful job not scratching anything. The advent system is about $500 for the kit. Good luck