you can try adding the following code at line 1 of the products_Results.php page:
<?php
if(isset($_GET["S_ProductName"]) && $_GET["S_ProductName"] != "" && substr($_GET["S_ProductName"], 0,1) != "\"" && substr($_GET["S_ProductName"], -1,1) != "\"") {
$_GET["S_ProductName"] = "\"".$_GET["S_ProductName"]."\"";
}
?>
it will force quotes around the search string.
it may be better, though, to add a message to the FAQ section explaining how to do an exact match search.