make them darker??

It is not recommended to darken your headlights/taillights, for safety reasons. Darkening them defeats its purpose--which is to be seen by others.

you can do it, but like Milliardo it'd defeat the purpose of having lights in the first place. On the other hand if you blacked out some of it (like left circles for the light to go thru) it'd be rad.

We tinted my friends stock tails on his 95 EX coupe and the light still shines through bright as fuck ... I will try to get some pics.

I ran tinted bumper lenses for a while until they were stolen .. here are some pics of that.
http://www.imagestation.com/picture/sraid43/p3f720b88e60e6402aaa6081897ee2c63/fce905c5.jpg

http://www.imagestation.com/picture/sraid43/pfb0453a8a3410ddf3437db9597b32cff/fce9059e.jpg

And here is my entire method
http://www.automotiveforums.com/vbulletin/showthread.php?s=&threadid=78479&highlight=tinted