You can't use PHP header to open URL in new window.
This is something that happens "client side", not "server side".
I have a question though ...
You're opening the new window from where?
If you're on a page and execute a PHP script, the server will overwrite your current page.
Or maybe you mean opening the URL in a new window with a link?
Is that what you mean?
A link like this?
$b8 = "Permit" ; $l8 = "http://www.mcfederation.com/FORMS/PERMITAPPLICATIONFORM.aspx"; $w8 = 91;
echo "<a href='$l8' target='_blank'>Open Page in new window</a>";