I just got my new system installed. SAS separates in front, Bostons in rear and Boston 10" in a small box. Sounds great, but small problems here and there. One-some engine noise when first starting and accelerating (esp.in morning) Also, I have left the factory head to maintain integrity of car, but am beginning to think that was dumb as hell. I have a funny crackling in all the speakers during quiet parts of songs like breaks, acoustic songs, or endings. The installer says its because I am amplifying a ****ty head unit. Can you replace the entire head unit??? If so, with what and where do I get the kit. Help me, thanks, joe