Ok i have a 2000 DTS that i am going to install 2 alpine m350 amps, (1) 4 channel amp, type 2 subs, and a avic D2, now i normally install my own stuff but i was told I need a special harness for the onstar, is this really needed? Reason why is that the onstar in 2000 was analog, now GM went digital, so it serves no purpose whats so ever. Also if i disconect the bose speaker do you think I can run my 4 channel amp to them. I really dont want to use the bose amplifier