HTTP/HTTPS Asymmetric-Routing iRule

Thanks for your response ,, I don't think it would work, as per my quick reading and understanding, the nPath solution is to bypass servers responses from getting back to the BIG-IP. I have Internet-Proxies behind my LTMs in both sites to serve the customers transparently, and each proxy will use the same customer IP to reach Internet. I was thinking if there is any method we can manipulate on http headers for example (of course not applicable for HTTPS) as most of the services configured on the LTMs are HTTP or alt-HTTP; i.e 80, 8000, 8008, 8080, etc. If we can manipulate http header by someway to stamp the packet with a specific value "Site-ID", and make sure this stamp/mark will not be overridden by any web server in the Internet, I believe this will do the job. Thanks & BR, Aziz