You can get HID kits that are only lo beam. I have a projector kit from luminous solutions that is hi and lo (same bulb) It uses some sort of reflector to angle the beam up for hi.

Retrofits are typically better because the give you a better beam and cuttoff.

The ebay headlights with projectors use the factory bulbs, which you could exchange for HIDs. I have heard of people having problems with ebay headlights leaking and melting, but those problems may have been fixed by now:dontknow:

I think I can answer your questions as I just finished my BHLM and projector retro a few days ago.

First off retros only use one bulb normally a D2S or H1. You just have to make sure you buy the right one they sell single (low beam only) and Bi-Xenon (low and high beam) the low beam has the nice cut off and for the high beam the shield inside the projector folds down to allow the light upwards. For our trucks you would need the Bi-Xenon to keep the functionality of your high beams. Almost all aftermarket ones such as those on ebay that I have seen use two bulbs normally an H1 (low) and H3 (high).

Using a retro you can buy plug and play adapters to convert the plugs on the HID ballast to D2S allowing your system to still remain plug and play or if you go with the H1 they will all ready be plug and play. With a aftermarket you will have to do a little wire work to get both bulbs to function as the high and low are separate.

With the retros you can also buy different shrouds to fit your style or give a more custom look. I've seen a few people on here even paint there shrouds.

Lastly in my opinion its not that hard to do a retro I have never done any type of modding on any of the headlights on the vehicles I've owned over the years until I did the X last week. It took about 3 days as I was in no hurry and the X is not my daily driver and I was also doing the BHLM at the same time. IF you do your homework and take your time its fairly straight forward.

I bought all my stuff at www.theretrofitsource.com. I used the HID kit I already had in the truck and just ordered the D2S adapters and morimoto mini D2S projectors with the Gatling shrouds. The D2S and H1 morimoto minis come with a H4 ring that allow you to install them with no cutting or modification just put em in and tighten them down it's that simply.

They have excellent customer service give em a call at 614.653.3451 they'll answer every question you have and if you order over the phone they'll give you a better deal then ordering from the site as they bundle stuff together. I only spent $300 including shipping for 2 sets of D2S morimoto mini's 2 sets of D2S adaptoers 2 wiring harnesses and 2 sets of shrouds and had it at my door 3 days later.

Hope this helps.