For sure foam filters are gonna restrict more air they also catch alot more floating particles, mesh filter doesn't block dust completely but its good enough...it does restrict some airflow but no where as near as much as foam. Mesh filters don't restict much but with a really low rpm fan you can feel the difference, compared to just having it free flowing. I mean even a finger grill is gonna slow it down some, but is so little to even care about. Just anything in the way any turns or anything in your airpath is gonna slow it down.