I've gotten pretty good at rev matching on downshifts. I can't really do with while heel-toeing yet though. I've never really needed to, as I'm only 15 and I've never driven on a track, but think if i could go to a couple track days I'd be able to get the hang of it. Something to remember is that some cars are designed better for heel toeing-than others. The NSX is a little harder to match the revs accurately on because the gas pedal is very firm. It's easier to modulate the throttle on my dads EVO, but then the clutch on the Evo is a lot less forgiving. I've tried to avoid situations where i need to downshift on my 944, because its old, the clutch feels weird and the tranny feels like somethings wrong with it, so by the time I got done experimenting and finding out exactly how to blip it the clutch would burn up or something in the transmission would go wrong.
I am quoting from Going Faster, Mastering the Art of Race Driving
from The Skip Barber Racing School, page 93 and 94 (their photo)
Since your left foot is on the clutch, and your right foor is on the brake pedal, you have to make some adjustments in order to blip the throttle. The way to do it is to adjust the pedals in the car so that with the ball of your foot pressing on the brake pedal ,there's a few inches of right foot left-over to roll your foot to the right and tap the throttle, blipping the engine up to the required RPM so that when the clutch comes out everything will be smooth and gentle. (see photo below)
This downshifting method is called "heel-and-toe" although, as we've just discribed, it doesn't involve your heel or your toe. The phrase was coined more than forty years ago, when many racecars had the pedals arranged so that the brake pedal was on the right, the clutch pedal was on the left, and [B]the throttle was between them and about six inches lower[/B]. Under braking, the driver had the ball of his right foot on the right-hand (brake) pedal and when the "blip" was needed, pushed down on the throttle with his heel - hence, "heel-and-toe". Pedal arrangements have changed but the term lingers on.
The pedals in most street cars aren't set up to facilitate heel-and-toeing, so drivers are forced to go through some real contortions to be able to touch the brakes and throttle at the same time. To do it right you have to do more than just be able to reach both pedals with the same foot. You need to accurately control how hard you're pushing on the brake pedal, a skill that's lost to many drivers who twist their feet into deformed postures to accomodate the awful pedal positioning in their cars."
And quoting [B]Jackie Stewart's[/B] [I]Principles of Performance Driving[/I], page 133.
"A word about the "heel-and-toe" technique for keeping the engine revving while you are shifting down gear. Heel-and-toeing never existed in the sense its name suggested: in real terms one just rolled the side of one's right foot off the brake pedal and blipped the throttle momentarily as required. Perhaps, way back in history, the initiator of this technique may have had a pedal configuration which literally required him to employ this technique, but the practical reality of the concept today simply involves the side of the right foot."
Great video. Sometimes you can find good race coverage that has split-screen imaging of the driver's footwork as well as the in-car video of the track. The two together is very helpful for those learning the technique.