interior - maybe seats but you'd have to modify the subframes and i doubt the rears would fit anyway; the rest; unlikely. Though i think you can fit a mK5 steering wheel. I've seen some install the MK5 headunit but it looks tupid as its wider than the centre console!
exterior - most of us fit the rear wiper, you can get the boot handle welded in and connected up
thats it off the top of my head
