Not much here except...
1. Do not buy the famed O2 sensor wrench that ECSTuning offers. It is a waste of money ($29.95) and is not designed to perform the task on an E46. It is a beautiful tool...but I dunno what I'm going to do with it......unless it would work for post cat. Didn't think of that.
Buy this.
2. Buy your Bosch sensors at Amazon. Check frequently for sales. I think I got both for around $150.00.
3. Take your time to ensure all wires are routed properly and plugged in correctly.
My take away......car runs very smooth.....noticeable difference. I swapped these out at 128.7k miles.
Elapsed time ~ About an hour.
Don't hate if you guys knew this. I had never done this before.
Good day!