I actually strapped a camera on my grill and recorded the shutter slats while driving. They didn’t close at all up to 85mph. I think they only close in cold weather to help warm the car up. The 85mph was only for a second, so not sure if they close at hwy speeds and long durations. Even so I wish I would have removed mine when doing the IC install.
Regarding Whipple vs others, just go Whipple. Mishimoto, or however it’s spelled, has had this teaser out for months and no true updates on progress. Zero drawbacks on Whipple’s design or performance.