So I got my system installed and two other shops who also looked at it can't get rid of the engine noise from the rear 6x9's. Both say it's the design of the vehicle with the battery in the back and alternator in the front. Every possible scenario was worked and reworked (including all grounds checked and regrounded and power wires run separate and the pioneer head unit was correctly grounded also) . The only thing i haven't done is changed the battery and alternator which they said won't help. The amps are close to the battery in the boot but when they connected another amp and moved it, that didn't help. Other people have had this problem. Any other solutions?