[Tommy]

Here are a few more words on the subject from an amatuer track day guy. One of the keys to getting around a track as quickly as possible is to approach the limits of traction. That means that during acceleration, braking and turns, you are often very close to the point of having one or more tires break loose. When a tire does break loose, you typically lose some control and your lap time suffers. ... When accelerating down a straight away and approaching a corner, you'll want to delay braking until the last moment and then maximum brake until you are down to the entry speed for the corner. If your speed has to come down a lot, you'll also need to downshift while you're braking so the engine is ready to provide power when the braking ends. If you downshift to a gear where the engine needs to be at 5500 RPM to match the wheel speed you are traveling, but your engine is at 4000 RPM when you release the clutch, the engine will try to abruptly slow down the rear wheels and can cause them to lock up. So, blipping the throttle at the downshift allows you to keep the revs up while you reengage the clutch. It makes the act of downshifting much smoother so the car is easier to handle when you are near the limits of traction. The need to simultaneously operate the brake, clutch and gas pedal is what heel-toe is all about.