I used masking tape, and a hobby knife and lots of time and patients.
Had to look from outside the body to see the body lines, and cut from the inside.Poke it with the knife a little to see where the tip of the blade is, and then just trim away.But you need a really sharp blade or else you'll tear the tape up.
I cut both vents out for even airflow.Nothing really to cool on the battery side(other then the li-po, but that never gets warm), but it's mostly for looks so it looks even.I did notice it kept the motor a little bit cooler.Use to be really hot that you could only touch it for a couple of second.Now you can touch it without fear of burning your fingers.(but still hot to the touch)
And by the way, your lambo body is nice!I like the one color scheme!