I don't shred, but I sometimes use a shred-style tone for more intense rock leads. I simply select the Hi-Gain Amp Model on my RP80, put on the most subtle chorus setting, and crank up the compression. It produces a tone quite similar to that of Chris de Garmo, if you like that kind of sound. In your case, you will probably get your shred tone mainly from the settings on your amp, but I personally think heavy, piercing lead sounds are best with some effects.