I am thinking about installing projectors in a 1999 oldsmobile aurora. The headlamps are pretty think but I think that I can get a bi-xenon in the middle portion. Anyway I would like some comparisons on three projectors. The first is a 2002+ e46 (3-series) bi-xenon, a 2002+ A6 bi-xenon dot, and a 2003+ A6 bi-xenon ece. First off, (1) which projector do you think has the best foreground lighting, (2) which projector has the best background lighting, (3) which prjector has the brightest overall lighting, (4) which projector is smaller and about how much smaller, and (5) is there a lighting difference/brightness difference between the ece and dot A6 projectors or is it just a different cutoff. I have seen both cars driving down the street but it is so hard to tell which car has a better projector.

Also

There is common agreement in experienced users that ECE projectors are more colorful and brighter than DOT. If I were you I would buy the largest ECE projector unit that will fit your retro. All those mentioned are very good. The Bosch bi xenon units in the E46 will probably be more expensive than the rest.

But you would say that the best/brightest projector to get would be a ece a6 bi-xenon instead of the e46 bi-xenon

Having retrofitted A6 DOT's and A6 ECE's, they both are the same exact dimension projectors. Both give off the same wideness and range on the floor. The difference between the two is that the ECE has a cutoff shield while the DOT's do not. Anyways, this isn't relevant to the topic. The huge difference driving at night w/ the DOT's versus the ECE's is that on the DOT, the cutoff line is not as sharp which allows light to bleed a little bit more; therefore causing light to reflect onto signs, roads, tree, and bushes. On the other hand, driving at night with ECE's, the cutoff is much sharper; therefore there is absolutely much less or no light bleeding above the cutoff for that extra light to light up trees, bushes or signs. If you were to drive with ECE's on U.S. highways like California where sometimes the roads are not even lit, you can't drive fast at night because you do not have that extra glare of light to help you see a little further like the reflectors on the road ahead of you. If you were to have the DOT's you would be able to see the reflectors ahead of you shine. I like the ECE's over the DOT's better in terms of looks and much more aggressive flicker but sometimes I regret having the ECE's because I have to slow down very hard when at high speeds whenever certain roads are not well lit. Sometimes, I think sticking to DOT's would be much safer for driving on U.S. roads because at least you can drive fast and be able to see what is ahead whereas if you had the ECE's and you are driving fast, then you better expect to slow down because you won't be able to see any reflectors on the road to reflect. With the ECE's it is very bad when you are going very fast at a ramp or on cruve turns downhill because you can't see anything on the sides or ahead of you. All that light is concentrated very sharply in front of you and you don't have any extra light to help you see the reflectors or anything ahead.

He is correct in everything he states but there is one more thing. Some ECE's have mirror shine polish inside the reflectors and so there is more brightness ahead. This has to do with DOT restrictions on HID output. The DOT hella bixenons for example have a rough finish in the reflectors. Nonetheless, they are still plenty bright. As far as Bosch or Hella, they both pretty much the same brightness.

All the projectors u mention has great output. The decision between ECE or DOT versions mostly a matter of taste. If u have been driving for 10+ years with DOT, it is somewhat of a change to use ECE. Its something u have to get used to.
What I would like to see is the usage of 4 low beam projector units where firsyt pair is unmodified, and the second pair is only lits up the road beyond maybe 30-50 meters. This is easily accomplished by adding a top shield.