This mod has been done at the factory on all SL's made since 2015. So, only applies to earlier models (mine is 2013). It consists of removing the diodes D20, and D21, and capacitor C56. You also have to install a jumper across two of the three diode leads on D21. I'll post a pic showing what I did. The effects of this mod are much more subtle than the sweep speed mod. Maybe a 5-8% gain in sensitivity in the air test on the 1 grain gold bar. But, still some gain, though I had to be paying atten