Quick question. What is the standardspeaker setup on a 2006 C230? My C230 seems to have outlets for 9 speakers (2 on the front doors, 2 tweeters in the front corners, 2 in the rear doors, 1 triangle in the center of the dash, and 2 behind the rear headrests). But the thing is there aren't any speakers in the 1 dashboard speaker and the two behind the headrests. Is this right? Thanks.