I figure wheel bolts are 12x1.5 so four 1.5 threads is 6 mm of engagement, half of the SCCA requirement. You are right it is reassuring to see that the wheels aren't going to fall off.
27Won instructions pdf includes a template to cut out and measure on your wheels to determine if a spacer is needed. 5mm is needed for OE wheels. No spacer needed for my winter wheels. You may not need a spacer with your new wheels.
Braking is much better! The brakes stayed cooler as well. The 27Won kit comes with street pads, I don't know what brand. No squeals at any time. Next year I might try switching pads for track days.
I have just installed the 27Won Big Brake Kit on a 2018 Civic Si with the OEM wheels. It required 5mm wheel spacers. There is 1 to 2 mm brake clearance with the spacers. As a result the lug nuts only engage 4 full turns instead of 7 or 8. This is not acceptable to me, especially for track and...