I hope this would help other brothers installing a car pc in their cars 
here are the links to my page where all the discribtion is with pics.
http://www.bimmer.info/forum/showthread.php?t=30429
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http://www.bimmer.info/forum/showthread.php?p=239860#post239860
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http://www.bimmer.info/forum/showthread.php?p=239863#post239863
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http://www.bimmer.info/forum/showthread.php?p=239865#post239865
by the way the front center speaker is installed in the front vents, the pictures will show, I also used the original car wiring I just had to modify the original car amplifier to utilize the conections and speaker crossover.
my next step is to interface the OBD to my computer it's that I can read the engine errors and reset it so my car keeps running good. I will also have access to the error codes just like the system they have at the agency where they test the car using a diagnostic tool. 