Great to hear from you, Pierrel. It's an honor that you're reading. - and, Welcome! If I'm counting correctly, that makes three 1.3 liter, four cylinder Swifts with 5-speeds on here now!
MetroMPG, I did look at your picture with great interest, and think my coverage is similar, except not the sexy one-piece deal like yours. I've been carefully watching my temperature, and it's not even pretending to get hot, therefore, I went ahead and covered the rest of the grille with more strips of tape (easy to remove if I ever need to). There is also a big open gap below the bumper/air dam thingy that's also open to the radiator, so there is access to air should the fan come on.
My latest little test has been to see what the characteristics of the cold start operation are. So what I'm doing is starting my stopwatch when I start my engine & also write down the "intake air temperature" and the "water temperature". Then I immediately start driving on a predetermined course, writing down both temperatures every two minutes. I do this for 10 minutes, which also puts me in an area where I can do a little mileage test at 40 MPH. So I turn around and immediately do a 40 mph run over a pre-determined course & log the mileage, then turn around again and do it the opposite direction. After that, I find a place to park, log the total time since starting the engine (about 18 minutes yesterday, 17 today), and the "trip" mileage for "today".
What I'm hoping to eventually accomplish is to establish some sort of baseline after a few days (these are my first trips of the day) that I can compare future thinner oil, Warm Air Intake, and/or engine block/transmission heater(s) against in the future.