I have no idea how they circumvent the rules, but trust me they are. I can show you "stock" SBC vortec heads that flow close to 300 and cost about $4500 bare. They use a port plug that is the same as the tech gauge and then play games past that. Math doesn't lie. 9.9 in a full size car.. What's that take, minimum 700hp? It's cheating on the grandest scale ever. There's circle track guys on here. They'll let you know.