the aftermarket drop in for the impala and monte are **** **** ****
they use a H3 bulb...a small foglight bulb about the size of the bulb that lights up our license plates. they will fog up eventually too, easy fix but its still annoying and headlights that cost north of 300 dollars should not fog up.
this is the light spread. pretty shitty huh. its decent light output directly to the front..everywhere else is dim
lastly they have pretty shitty QC as well. Alot of guys have reported the adjustment screws dont work when they received them or they strip out easily.
IDK, I guess they look pretty cool when the lights are off, the rings are pretty bright, but they look ricey when theyre on..doesnt really go with my cars. I ditched mine last summer for the stock housings + HIDs.
as for retrofit...I know someone here just did a retro on some GXP housings..