Today, I pulled the OEM mechanical fan and shroud and installed the electric fan with variable speed controller.
So far, it's much quieter. Can't really tell any difference on the road. I'm going to be driving about 1000-miles this week for work, so I'll have some good checks on MPG. I made the same trip this past week. We'll see if there's any difference.
One thing I did notice is that if idling, it will take a good 10-min for the truck to build up enough heat to kick the fan on. The radiator stays cool for at least 6-7 minutes with no sensible heat at all. Once the fan does cut on, it does so at a low speed - just enough to keep temps in check.
Also installed today was a set of DDM 55W HID lights, 4500K color. I got them with the relay/harness and installation was a breeze. The oem reflectors in the Hundy's have a great low-beam cutoff, and so using HID's in the stock housings isn't an issue.
Light output is amazing. The 55W HID has around 5X the lumens as a 55W Halogen. I'll get pics of the beam, etc up later this week.