[LeanBurn]

My full upper grill is permanent, it was mounted in front of the grill, but it got so plastered with bugs etc, it looked awful even in black. So I took the time and mounted it behind the grill. I saw zero difference in fuel consumption in front or behind.

My lower partial grill block is mounted in front of the grill. It's only for cooler months. Since I have a full chin-to-radiator pan I can't access the rear of the lower grill for securing zip ties so I just mount it from the front allowing a 2 snip removal when needed.

I have a 99% block on the Buick mounted to the front as that was easiest to accomplish. The bottom is full open.

The Suburban has a 50% plastic mesh inserts meant to filter out bugs, also mounted in front.