How does Special Move art power work exactly?

Hey, Ryuji here.
Helped with the adjustment and testing of the calculator.

The recent released SP 1 form Frieza has a main ability which increases the art power by 50%. According to the article on how damage works in DBL, 20 art power equals to 7.7% increased damage.
Frieza main did increase the special move power by 130 art power. The damage increase was 16% instead of 50% it should have been.
The unit was not fully boosted.

So here is what I think:
Either the increase is bugged, or special move increased art power uses a different formula. We know that the suicide awakening card art power increases the lower your health is. It could be possible that the higher the special move art power is, the higher the % of stats it uses to calculate the Special move damage increases. That would explain my on my test the damage was low.
That or it's something else where I'm completely clueless.

Currently low on ressources and can't fully max him to do further tests.
Cheers