They were right about the metal firewall but you will still hear it. My dad had a 1990 525i that basically became my first car. First system-2 JBL 12's in that car...then put 4 Kicker comp12's in it. Heard it pretty well.

And as for awesome shops....most knowledgeable people on here say Sensous Sounds or Audionutz in ocala...I went to AVE Audio in clearwater all the time cuz it was close to me and for a real small shop they do good work imo.

BTW I install for CC. Dont believe whatever their sales people tell you. Few really know what theyre talkin about. Go get the opinion of custom shops first.