well im not sure if the speaker set up or use is the same as in a 325 but check the FAQ forum , it has the 3 series speaker sizes in there. it may help you out.
yes, they are 5.25 front and back, 2.5" or 3" dash, 1" door.
it is a 10 speaker system beacause the rears are supposed to be a 5.25" and a 1" per side. thats a total of 4 in the rear, and 6 up front.
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