Have you already cut them in? I had 'em on my 1st (purchased) -4, & they were quite noisy because they are pretty close to mic height in the cockpit.
On my 2nd (purchased) -4 there was already a naca duct feeding an eyeball vent at the instrument panel, but nothing for the back seat. I bought the RV-10 vent kit (2 for one!) & installed half the kit in the side skin below the top longeron. When opened, it pushes out into the airstream. Works great; much quieter. If you need pics, let me know.
Charlie
