I agree with what you're saying Ron, and I don't want to join "vacuum leakers anonymous" by conducting the experiment, but...the way Dan describes it, this particular setup is not a leak and in fact only works if there's no leaks and there's good vacuum. It sounds like he's been doing this on vehicles that have been grooved and has been getting an increase in mileage (correct me if I'm wrong Dan), so IMHO it warrants investigation rather than automatic rejection. Essentially it's still a capped vacuum port, but with a partially filled fuel filter between the port and the cap, creating a simple vacuum based vaporizer.
