Thunder Calibration

[NightViper19]

Does anyone have advice on how to calibrate the Thunder? Like Advance K, e-steps, etc.
It should be easier than an Ender 3 or Mizar, but the proprietary firmware and closed loop drivers give me pause.

Originally I asked the GeeeTech tech support about the Thunder calibration, like Linear advance and such, since my Thunder has TERRIBLE corner bulges. They said that no such thing exsists. Then I find the Smartto software through the wiki that has an Advance K setting. Normally I would run a Marlin Advance K test print lines and I would choose which one looks the best, but all the lines look exactly the same!

Any thoughts, or stuff you guys did to make your Thunder print better and be dimensionally accurate?