On the magnet cover, I just went to look at both my speakers. Both are covered by plastic. So far (after 3 mths and 4.6 kmiles) have not noticed any problems with the CD Changer or Power Amp. Any comments from the others ? I am curious why yours has a metal cover. On mileage, after this tank I will try 89 Octane to see if there is any difference. Regards.