Getting ready to change fluid to either ATE or Motul 600.

I think that I need 2 liters. Is this correct?

1 liter is sufficient. However, unless you're changing colors (e.g., amber to ATE Blue), it can be difficult to know when the new fluid starts to bleed out so most people end up over flushing.

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Dan

On page 301 of the 2007 Owner's manual it lists all the fluid capacities and it states:
Brake Fluid - approx. 0.4 quarts/0.39 liters; use only Original Porsche brake fluid

I changed mine and used perhaps 0.75 of a litre, so have some left for top ups when the brakes wear in.

2 litres would be useful in the case you screw up, (tipping the can over, forgetting to close the bleed nipples completely, dropping the can causing bubbles to form........ )

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Cheers Karel

'Power is Nothing without Control..........'

I used nearly two liters.

This included a good flush and bleed of the brakes and clutch (same reservoir), followed by a test drive with hard braking to cycle the ABS pump, and another bleed to ensure that all air was gone (one air bubble in the right rear).

I suggest you purchase another liter and leave it unopened so that you have "fresh" fluid available in case you need to bleed your brakes at the track.