I am leaving the mesh on. I think it will keep anything from getting down in to the engine if it ever got through the air filter. Like chuncks of dirt,mud, sand build up,small sticks and what not. It is a good protective barrier and i go wheelin in the Carolina woods every other weekend. Stuff gets nasty out here quick aspecially if it is a little wet. An easy trail can turn in to a challenge with the varying weather we have here. I do plan on putting a TRD CAI on one day but right now everything is pretty much stock aside from the HCDelete. Yeah, i would keep the mesh on it serves it's purpose but the Hydro Carbon Filter not so much. Unless you are really concerned about a little bit of gas vapors burning up and getting in to the atmosphere but i think it is ironic that here in the south they still let people out in the country burn there trash outside. Stinky, oh yeah and i did notice now with the filter gone i do not get as much of the sulfer smell but it is still there if you get on the gass on a hill or for any other reason. Just keep that back window up or get a side exhaust system mine is still stock with the resonator coming out the back.