OBC functions with Nav Screen removed

[mac500]

Hi guys, drive a 2005 3.0d E53 Sport. Fantastic car but the audio is woeful.
I have upgraded the speakers to components in the front 6.5" composites in the back and a 10" sub in the boot.
I run these with Alpine V12 amps.
By rights I should get a good sound but to be honest, it isn't good enough.
I have considered changing the whole lot for aftermarket head unt, iPod, Nav etc but the thing that stops me is the loss of the OBC reset functions and the Aux heating timers.
Is there ANY way I can get round this as the Hifi is doing my nut in (Driving me crazy!)
Ps, this forum rock, you guys seem to have a big modding community compared to us here in the UK and I have seen some superb ideas from your side of the pond, hopefully, one of you geniuses can solve my little issue!!

Regards

Mac500
Oxford England UK