How to downgrade the BMW Nav software on e65/e66?

I like the way it's working on v27 which was original on my car (DVD v2006.2)? I downgraded it from v32 (DVD 2009.1 and 2010.1), when the sofware CD v27 is inserted it shows the right version for v27 but on the map it's still the features of v32. Unplugging the battery didn't help. The current version shown on the display is 9.8.2 and originally it was 9.3.C. I loaded v27 back from a CD so it's showing 9.3.C and OCM 2030 but the nav map has a look of Nav DVD w/ v 2010.1 although I put back original DVD v2006.2 after I downgraded the software.