Go with OEM. The KBMWSIRV2 kit does not display artist information, radio station name, and song name on your oem headunit. You'll see something like CD2-10 (meaning station 210). Check out the mfr's spec right here:
http://www.tss-radio.com/images/soundgate_kbmw.pdf Of course if you don't care about that then $180 gets the job done.