Formula for Weird Science burn out in 928.
 

Porsche 928 - Excellent Peel Out - Weird Science - YouTube

Automatic:
Hold foot firmly on the brake with car in drive. Press the accelerator to the floor until the rear end cuts loose. Then let off the brake and continue to floor the car.

Standard: Hold clutch to the floor with the car in first gear. Press accelerator to the floor and dump the clutch.

Any questions?
Note: Probably not a good idea in a 27 year old 5 speed.

clutch dumping isn't necessary on an otherwise healthy 928: just let the clutch out quick as you're reving the engine: 3-4k usually will blow tires loose anyway. :)

See here in my 3 famous burnouts:

Supercharged Porsche 928 - YouTube

porsche 928 burnout 2 - YouTube

928turbosports.com turbocharged 1986 928S doing a spirited launch - YouTube

Nice

Is that in fact the stock sound of a 928 in the movie? The "pumpkin" in my 81 Euro is so rotten that it seems to leak more exhaust through the numerous holes in it than through the tips. Am I losing performance with the degraded sound quality?

I don't think it's the stock sound in the movie. It sounds a little too beefy to be stock. However you are probably losing some of the performance from the rotten pumpkin. My '83 has a megaphone in place of the pumpkin, and though it sounds raucous, it doesn't have the power that my '84 with the ANSA pumpkin has. There have been lots of conversations on here about back pressure and the pumpkin is useful for that.