I recently sold my 2000 328ci and bought a 06 325i (E90).My 4th BMW,and my favorite so far.I made a great deal ,as the car had a couple issues.One being the stereo,although working fine,had become pixelated and impossible to read the display.I purchased another Professional CD/receiver out of a 2008 335.The unit is identical and was a straight swap.Everything on the new unit works and the display is bright.However, the volume is low and will not turn up using steering wheel controls or the ones on the unit.Is there a code or re-learn on these units? The BMW part numbers are different for each unit.Is it possible that I have to get a unit out of a 2006? Thanks for any feedback