[BirdOPrey5]

I've never seen a mod but I was able to pull it off with a quick template edit-

Edit the postbit_attachment template.

Add the code in RED. (or replace it completely with the code below)

<tr>
	<td><img class="inlineimg" src="$stylevar[imgdir_attach]/$attachment[attachmentextension].gif" alt="<phrase 1="$attachment[attachmentextension]">$vbphrase[file_type_x]</phrase>" width="16" height="16" border="0" style="vertical-align:baseline" /></td>
	<td><if condition="$post[reputation] > 15"><a href="attachment.php?$session[sessionurl]attachmentid=$attachment[attachmentid]&amp;d=$attachment[dateline]"<if condition="$show['newwindow']"> target="_blank"</if>>$attachment[filename]</a> ($attachment[filesize]<if condition="$show['views']">, <phrase 1="$attachment[counter]">$vbphrase[x_views]</phrase></if>)<else />Your reputation is too low to download.</if></td>
</tr>

Notes- This will only work on file attachments. Image thumbnails have their own template you could make a similar edit.

This will stop 99% of users but if someone knew what they were doing and knew the attachment ID they would still have permission to download if they manually entered the URL into their browser instead of clicked on the attachment link.