I did not say Porterfields R4S pads are the best for the street or autocross.

They really are a high-temp pad. Fad resistance is excellent, they are but trying to come to the first stop on a cold winter day is SCARY! With a car the weight of the Xfire, auto-x may not heat them up enough to get them into their ideal operating range.

I ran the R4S pads (not R4 pads) on a 3600 lb Supra. They fixed the problem I was having with overheating the OEM pads, but they were no good in the winter. If you don't drive in freezing climates, you'll be good to go.

I prefer the Porterfields to Hawk HPS pads though. The friction level on the HPS pads felt low. The OEM pads on a BMW Z3 had higher initial friction that he Hawk HPS. The Stoptech pads Needswings sells look interesting.