Hi @marcopolo

I've just tested it, setting my own IP as the test mode IP & can confirm it works on subpages. As far as I'm aware the index.php always fires, then loads in templates, includes etc. It may be a more elegant way to load it, as the block will launch with minimal code being loaded, possibly reducing server load in the process. I chose index.php as according to the program flow in documentation it's the top level page which everything else loads from. With this being a blocking script, it would make sense to expose as little code/server resources as possible.

Program flow docs https://docs.zen-cart.com/dev/code/program_flow/

I also set the redirect as a 403 forbidden error as this seemed more appropriate for my usage.

Code:
// Redirect to the 404 page
            header('HTTP/1.0 403 Forbidden');
            zen_exit();