I have the K2 installed on my K1300GT. I also have a DAB/FM radio and a Ham radio (144/433 MHz) :-)
After I mounted the K2 on my MC late last year, I have had some interference on both the DAB/FM radio and my ham radio. It is like pulses with 1 sec interval. I have spend some time tracking this down, and it shows it is actually the K2 that does it. The ham radio also has receive capabilities on Air band (118 MHz / AM). Here the K2 totally blocks the receiver. Signals have to be very strong to overcome this interferences and it actually does not sound very well.
As soon as I turn the K2 off, the interference disappears.
I have tried with a handheld radio to move around the MC, and as soon as I get near a K2 component or cable, the interference is very strong on the Air band, and noticeable on the ham bands.
It is most prominent close to the K2 box or the GPS module.
Normally i would start filtering power supplies to devices, but as this is radiated from all K2 units and cables this is impossible.
In certain situations this is unusable for me, and I will have to mount a switch now so I can turn off the K2 :-)