Mesh Grill Hole Sizes Air flow Restrictions

ZPWR

Yo Fellow Zs. Just have a question on whether adding a mesh grill, particularly one with a small hole size (ie 6mmx3mm) on our front bumper generates some form of air flow restriction and if so will it impact our cooling efficiencies? ie Radiator, Oil Cooler, Trans cooler, Power steering cooler etc.

Thinking of DIY'ing one for my OEM front bumper due to some stone chip damages on my brand new setrab oil cooler that I would hate to replace so early just because of a few rocks that dented it and causes oil leaks in the future. Worst case scenario ofcourse.

What would be acceptable mesh grill hole sizes? On a side note does anyone have the Stillen front bumper? Looks like they come with pre-cut mesh that fits perfectly. Plus I really like the look. Heard some bad reviews on them though. Hopefully they're not true.