Yes, you can change the text and font size.
In siggy.php look for this code:
PHP Code:
$str1 = "Name: ".$name;
$str2 = "Owner: ".$owner;
$str3 = "Click Here to Feed Me!";
$str4 = "More Adopts at:";
$str5 = "www.".$domain;
imagestring ($image, 12, 0, $textheight, $str1, $color);
imagestring ($image, 12, 0, $textheight + 13, $str2, $color);
imagestring ($image, 12, 0, $textheight + 26, $str3, $color);
imagestring ($image, 12, 0, $textheight + 42, $str4, $color);
imagestring ($image, 12, 0, $textheight + 55, $str5, $color);
The 12's in the code are the font size. The other numbers, such as 13, 26 etc control line spacing. You can edit the text in the $str variables to whatever you want. :)