For those users with High wind chimney caps (dealer suggestion to buy) using a Vacu-Stack 6inch cap Pros and cons! All I can see is this style cap controls down draft but how does it control wind and still maintain min -max draft? http://www.woodlanddirect.com/Vacu-...clid=CMnL7deZwtECFQkOaQod48sF5A#Vacu-stack:6"