Update to PR 1.3.1 via OTA. Install CSSU Stable from here. Select the yellow stable icon to download via MicroB. You can't switch between PR 1.3 and CSSU, and there is no need to. CSSU can be removed and PR 1.3 reinstalled, but this may break some dependencies due to the extra features of CSSU. Best to reflash in this case. Swappolube is also worth installing and load the proposed settings.