Batboard

With the dual heads installed on both a VHF and UHF set in my Fire Chief's car we are getting wicked noise through the rear amplified speakers from the engine - The filters are installed - any ideas. And why does the rear Speaker need to be such a big amp ?

I am going to be installing the same setup in an ambulance.I ordered the rear control package and noticed the hefty dc filter. My first thought was, Why? Now I know. If anyone knows something we don't ,please respond.
Thanks

Where is the filter installed at. If it is to far away from the head giving you problems, you will get Interferance between the Head and Filter. I know it's a simple answer but sometimes you just got to check.