So over the past 2 days I tested the 416 against a couple of Infinity controls. The results improved within the 75 CFM range of one another. With the formula provided by Jim, CFM was even closer. I guess I must have done something wrong to be off like I was before.
Jim, should I be using the traverse chart on your site for the 416 or split the return duct 3 ways as even as possible? I've been splitting it as even as possible.
Thanks for all the responses!