Thing is its not just a NAV unit, everything else is attached to it as well, climate control, A/C, phone, CD & Changer and the auxiliary audio socket in the glove box so it all has to stay really ... the unit seems to deliver enough power to the speakers, they don't distort they just don't produce very low frequencies and sound like they produce a bit too much mid range.
As for the car, love it, a nice upgrade from my ST200, surprisingly quite a bit more torque as well.
Few differences such as the 6th gear, that took a bit of getting used to and the closer ratios but that's all good now and I love the popping from the exhaust on downshifts and lifting off the throttle, not too loud just nice and how the exhaust note changes depending on the rev range, it seems to be a very well tuned custom exhaust.
Fuel consumption is about the same as my ST200 was maybe 1-2mpg less but hardly noticeable.
The ride is much better, there is less body roll, its firm but absorbs bumps very well, handles amazingly, great feedback from the steering which I would say is on the heavier side for power steering but I like it, you get a better feel for what the car is doing.
All in all I am very happy so far, glad I never chose a ST TDCi I'd have hated to loose that V6 soundtrack..!
Stu