I recently sold my 435xi. The BMS stage 1 tune (harness B) was installed on the car for about 6 months. It's a great tune, and really easy to install and remove (unlike the JB4 that can be a hassle to remove). You can definitely notice the power increase, and the throttle response improvement, it's totally worth it.
The harness and the computer chip are in great condition and practically brand new. I am offering it shipped for $280. Brand new this will cost you $393 ($379 + $14 shipping and handing), so you will be saving more than $100.
http://burgertuning.com/N55_Jb_BMW_P...nce_Tuner.html