The graph actually confirms what I am saying about the Porterfields.
You need to get them hot to make them work. 300F is very hot if you ask me.
This doesn't build confidence in the brakes when you jump in the car and just want to go around the block in it.
It would actually be nice to see that graph continued with other alternatives in comparison but I think the source IS Porterfield themselves.
I think to put the temps in perspective, header tubes will start to glow red around 700 degrees.
The temps needed to be "effective" for what you paid for concerns me in say a wet driving scenario where the rain is keeping the brakes from even warming up to 300?
As BWrench says, it really is a matter of testing different pads to find what you like?
Looking at the chart again, there isn't much difference between the R4 and the R4S as I read it and the R4's are DEFINITELY just plain dangerous on the street.
Not everything "high performance" is better.