OEM Satnav or Upgrade headunit

[TomTom]

What I'm after is a reliable satnav functionality and ipod connectivity. At the moment I've got a GROM unit but I'm dissapointed with it because of the hit and miss on the wheel controls (unfortunately my unit doesn't let me use the wheel controls to change my music), but it provides iPhone charging which is the main thing.

So I've been tossing up to either get an OEM Satnav installed, assuming Subuaru would still do this? OR upgrade the Mcintosh head unit to something that will have satnav, usb for ipod connectivity, work with the wheel controls & easy install.

I'm happy with the sound quality and bass in the current system, I've done enough damage to my ears with my previous car & sound system and the GF agrees (always blaming me for the ringing in her ears).

Suggestions? If anyone's got a rough price on the OEM Satnav i'd appreciate it.