no mods on the factory preset. it is a clone of the drive channel that is stock on the old slo 100. it is bright like the original. the warren mod was used to darken the amp and tame the high end bite. the can be done with the eq on the eleven rack to filter off the highs and result in the same effect

the stock amp has a "brite" bypass cap soldered to the drive channel's gain pot. The mod is simply to remove that cap. This makes the overdrive channel more useable at lower settings of the gain knob, where that cap can make the tone too bright