I want Google search results to default with a publish date. I'm trying to change the Google search plugin, but I'd be just as happy using a 3rd-party tool that does this.

So I'm using Firefox 15.0.1 and I've tried changing {install dir}/searchplugins/google.xml, but Firefox is just ignoring these changes.

For example, I'm adding the below in 3 places in google.xml, but nothing is happening:

<Param name="cdr" value="cdr:1,cd_min:01/01/1900,cd_"/>