Hi Schatten-

I've used the R4 but not the R4E in the past.

I prefer the Hawk compounds. The Porterfield pads aren't as consistent from batch to batch. Sometimes I got a great set of R4 pads, sometimes they totally crapped out quickly.

I've never had that problem with Hawks. I consider Hawk to be a more racing oriented company, and Porterfield to be an enthusiast's company. Hawk is part of a trio of companies comprising of Tex transmissions and Quartermaster clutches I believe.

For what it's worth, I use OEM pads on the street, but then again, I drive like a granny on the street too...