Sorry I was a little wrong with the term complex....the HIDs are plug and play but from what I remember (it's been a while since I researched) people were having problems fitting the balast in the housing and also having heat issues.
The LED conversion is the one that's complex as the canbus system needs to be satisfied with a certain voltage. There's a complete writeup on what relays and whatever else is needed to make them work on the Cummins forum.