Pre facelift V Facelift
 

What is the actual difference in build to a Facelift and pre Facelift 4.2 tdi

I know the engine has a higher factory HP and 50nm more torque but ... why is the engine much more quiet than PF ? I drove one the other day and it's either a better insulated cabin or the engine build and design is actually different in some way.

Other differences I'd be interested in is sound system... my friend has a 2016 S8 and mine is 2012 .. his bose sounds like a different system to mine, using the same SD card track as a reference it's almost hard to belive they are even the same system at all ... ??

I think the difference in sound system might be just the firmware.
I can not really hear my 4.2tdi from inside, not sure how much quieter can it be, mine's 2010