I have a 23 Silverado ltz with Bose and big screen I have speakers from an old truck for front, rear doors and dash. Is it a worth while upgrade to replace stock bose speakers with my Hertz speakers which are 4ohm and very efficient, 92 db with stock amp. My installer is waiting for a harness to add a 6 channel amp? Would this improve sound? Would I lose any chimes, etc? Would things sound distorted? I also wanted to disconnect factory sub and add a kicker mono amp and sub? I want to run the sub from 25hz to 250hz. Installer was going to take signal from back door, run it into kicker keyloc and then amplifier. Thanks.