The 944 brakes certainly need pushing harder than many over servoed modern cars, they should work fairly well though. My coupe has Big blacks and EBC yellow stuff - they squealed comically until I got some proper heat into them (black flagged at Donnington and sat there with them smoking for 2 minutes while they came over and told me I was being too noisy - exhaust was popping as I changed gear under the noise sensor). Yellows wear slower than Red / produce less dust and work better and are fine on the road after cooking. I have some yellows to try in the Yaris at some point not because the standard ones are lacking but because I won them (that has 356mm disks from the factory though which is pretty big for a fairly light car).
Tony