The 722.3XX can be made to handle quite a bit of power..Especially that later 722.350 & 353 come set up to take 333hp from the factory.
I have also heard of people installing an additional clutch plate (I believe the transmission in my black coupe is a 722.350 w/ 5 plates over of the stock 4).
The 928 guys are putting 5-700Hp through their 722.3's.
I've heard the same thing MB Doc mentioned about the 722.5..thus why I'm looking to install a manual
Jonathan