Why don't you just start with the Phillips Xstreme Vision bulbs which would be a $30 experiment to see if you really need more light than that. They claim 130%

 

Thanks Wilson, I replaced all four H7 bulbs w/ the Philips Crystal Vision Ultra Headlight bulbs. Yes, improvement, but still unacceptable output. Plastic cover lens also polished which also helped!

 

Fog light LED helps already.

 

Personally, I do not care for putting LED "bulbs" into existing fixtures. LED light is very directional and requires multiple lenses to spread it to an acceptable pattern. Cars with native LED lighting generally used multiple bulbs and lenses to create a proper light pattern. Most of the time, putting an LED bulb into a halogen housing results not only in blinding other drivers, but poor illumination from the driver's perspective.

Halogen and HID bulbs produce omni-directional light. You can put HID bulbs into any lens designed for a halogen bulb and it will work and the the driver will get great illumination, but it will totally blind other drivers. The exception to that is when the housing is a projector lens instead of a reflector behind a clear lens. Most all projector lenses use a shutter that creates a sharp cut-off so that light from any type bulb will not blind oncoming drivers. I have put HID bulbs into the ML's projectors and it woks fine. I compared the beam pattern and oncoming light to my SL550's stock HID's and it is identical.

As for fog lights, if you want them to match the color of your HID low beams, feel free to put LED bulbs in them. You may not get good illumination, but they are fog lights and not as critical in terms of illumination, plus they are aimed low not to blind oncoming drivers.

 

Personally, I do not care for putting LED "bulbs" into existing fixtures. LED light is very directional and requires multiple lenses to spread it to an acceptable pattern. Cars with native LED lighting generally used multiple bulbs and lenses to create a proper light pattern. Most of the time, putting an LED bulb into a halogen housing results not only in blinding other drivers, but poor illumination from the driver's perspective.

Halogen and HID bulbs produce omni-directional light. You can put HID bulbs into any lens designed for a halogen bulb and it will work and the the driver will get great illumination, but it will totally blind other drivers. The exception to that is when the housing is a projector lens instead of a reflector behind a clear lens. Most all projector lenses use a shutter that creates a sharp cut-off so that light from any type bulb will not blind oncoming drivers. I have put HID bulbs into the ML's projectors and it woks fine. I compared the beam pattern and oncoming light to my SL550's stock HID's and it is identical.

As for fog lights, if you want them to match the color of your HID low beams, feel free to put LED bulbs in them. You may not get good illumination, but they are fog lights and not as critical in terms of illumination, plus they are aimed low not to blind oncoming drivers.

Thanks Rodney.
Great background info. The person at Retrofit Lab is selling the whole kit, which includes the Bi-Xenon projector unit, not just the Xenon bulbs, so I am optimistic that it will work. Was just asking the members if anyone successfully did the upgrade and alignment/aiming by swapping out/in the projector assembly (pictured)

 

.....

 

I've done an HID retrofit: discarded the halogen spec projector and dropped in a bixenon from an E55. Note that you'll be baking open your existing headlight, installing/aligning, hooking up high voltage ballasts, adding a relay (recommended, some do not) and ensuring the the alignment of the beam is to standard. I performed this on my 1999 E320 which is probably a tougher project than with your ML (my guess). Bottom line is that the undertaking and skill set required is not for beginners without decent knowledge of car and electrical workings.

 

Thank you everyone for the helpful suggestions and references to very good videos (was especially impressed with the one showing re-coating everything with Armor Shield clay (E55?). It looks like the "baking" job is is something I don't want to take on due to my limited work space and time.

I am looking to buy some new DEPO (halogen) headlamp assemblies and bi-xenon kits and would like to find someone who would do the conversion, for $$ fo course, preferably in the US (I am in Colorado).

TIA.