I tried searching for this but didn't see anything.

I read on some threads about doing the washer mod for headlights. what is the washer mod?

What type of car? E36? Here's some info about a modification to supposedly improve the windscreen washers:
http://forums.bimmerforums.com/forum/showthread.php?t=438722&highlight=washer+notes

Or, maybe you're thinking of retrofitting headlamp washer jets - on some models (such as E36) these were available in Europe but not in the US.