I believe Maximum overthrust is bugged for the following reasons
Maximum overthrust:
Effect: Use Zeny to increase Attack Power during the skill's duration. Unlike Over Thrust, this skill only affects you. There is a 0.1% chance to break your weapon with each hit. ATK increase is +20% per SkillLV.
Cart Termination formula
(Weight/6)% Attack, 1500Z spent, 50% Stun Chance
according to this info and multiple boards I have checked on. This current svn Cart termination is supposed to stack with maximum overthrust as in you get the extra power.. but for some reason when Maximum over-thrust is used the atk does not rise but instead only when you meelee someone will you see the double atk.. Maximum is supposed to raise your attack so you can use it in unison with skills such as mammonite and cart termination. Could you please look into this Thank you