Trying to understand appropriate routing in MVC
Have you thought about calling the overview only when the URI ends in "overview" and preceded by a product slug?

$controller = new Controller();
if ( preg_match("#^/([a-zA-Z0-9_-]+)/overview/?$#", $uri, $matches) ) {
    $controller-&gt;showOverview($matches[1]);
}


This way, you define your routes with the following assumption:

/:product
/:product/specs
/:product/comments
/about


You should check out the Slim Framework: http://www.slimframework.com/

I've used it just for routing when performance was a crucial requirement.