Don't bother with removing shims.
Go to your closest dealer and order the variator shaft for a MXU300, any year, like a 2015.
Replace the shaft and then you have full power. You can unscrew the throttle stop all the way then.
BTW, if you have the stop unscrewed with the clutch still restricted, it will over rev, get hot and melt things.
Good Luck
Chris