I've installed a few sets ( at client request ) on E46 and E9x cars. The coilovers are standard issue Manupackager coils, just finished in the color way of the company you buy them from... These all come from the same overseas factories.

They can get you low no problem, ride quality if what you should expect for something so cheap ( poor ) and they are woefully underdamped and boingy going down the road.

 

That's what I've heard about ECS Tuning's first coilover set that didn't dampen worth a damn. People said they were bouncy and they didn't like them at all. But they said this newest version has several different dampening settings that work really well. Have you specifically installed their newest coilovers on any customer's cars? They claim the ride retains stock comfort level but that they handle better than stock. Even visually these look like a different style than the original ECS coilovers.

My main concerns are height and ride. I don't want the ride to be much different than stock (which is what they claim), but I also want to make sure they don't lower the car too much. I don't want to lower it more than about 2" in the front and an inch or so in the back. I don't want them to top out over bumps. I doubt that'll happen. I've only had one set that does that so I think it's rare.