I use an Autocom Smart 7 Zorroe. It's about the size of a cigarette box, permanently bike mounted and currently it deals with pillion, mp3, mobile phone, sat nav and 2 way rad without problem. The whole Autocom range has been updated around 6 months or so ago and it's easy now to pic up a full kit off ebay for a few quid.
BUT-they also do a larger version, the name of which escapes me. Barsteward has one and the main difference seems to be that the unit itself can be battery powered and a 2 way radio can be powerd from the Autocom itself. You can't do these things via the smart 7.
The setting up is the key thing with any Autocom. The electrical connections and mounting for the Smart 7 are childs play, but when I piled on the phone, music etc all at once I couldn't get anything to work right
The art of it was easy enough though- Take yer time. I unplugged everything and put em back on one at a time until they were right.
All instructions and manuals for wiring and set-up of Autocom units are available to download from here:
http://www.autocom.co.uk/
along with the prices for their latest units. Always your call m8, but have a serious look at ebay, the units on there are very cheap at the moment for the older S 7 and pro units but the quality is still up there with the best of 'em
Last thing m8- you may have to buy various cables as extras from Autocom depending on what you're wiring in to it but- whatever else ya do try and make sure you get two helmet kits with yer system, to buy a helmet kit for the pillion is the best part of £100 (or was when I had to get one) so get everything ya can with the unit itself.
Good Luck- any probs ya know where we are
Eliminate the impossible. Whatever remains, however improbable, must be the part you forgot to service.