The ZC headlights are almost identical to the USDM headlights, except I think they are plastic (which id rather have glass)... But they look exactly the same, and fit the same... Edit: And they only have one bulb compared the US, has a high and low beam... (forgot to add that)

The SiR headlights are wider and taller (for the hood that makes room for the B16)...

SiR front end:
http://www.passwordjdm.com/uploads/i..._large/345.jpg

And in 90-91, all JDM CR-Xs had the SiR front ends... So the ZCs only come with a 88-89 bracket which is different than the 90-91 USDM bracket...