I just did this on my 06' 325i with 127,000 miles (original plugs since new)...
Went to Momentum West in Houston to pickup 6 new plugs (LIST: $37.25) at $21.96 each part number 12-12-0-035-915
Also picked up Microfilter (LIST: $85.42) at $50.92
Part number 64-31-9-142-115 3022A
Out the door for 6 new plugs and micro filter and tax: $197.75 NOT BAD!! Considering they charge $250 for microfilter change.
Anywho... The install went fine and my cold idle is 10000000 times better, power is better, gas mileage better, acceleration better. Its like a new car!
The new microfilter fixed my mister, I mean AC and also corrected my surging HVAC....
All this good news even with temps in the 108F the past week! I can't wait till it cools down.