Yes, I did read the manga. But, reading it doesn't mean that Arima is objectively faster.
All you need to do to have subsonic speed is to move faster than the eye can see, which we see multiple times (specifically with Levi) with the 3DMG.
The only case I see ghouls being supersonic is if they dodge bullets, but since most cases are aimdodging, this would put them on the subsonic side of things. Plus if there are ghouls with supersonic reactions then it's not on Arima's profile. If you want to change that though, there's always the content revision thread.
Give me proof Eto in base is faster than Levi, or any other ghoul actually..?
Yes, Levi doesn't move at supersonic speed, but instead he fights with supersonic speed. You forgot one thing. Levi not only has supersonic reactions, but supersonic combat speed too, which is how fast he can fight with his own body. For proof, some professional martial artists may fight with subsonic combat speed, but can't run as fast as Usain Bolt.
Calculations are a guideline to see where a character may be with proof. You can't just say that calculations don't prove that someone is faster than the other. Arima is at least subsonic+, yes, but since "higher" is unquantifiable, you should still expect it to be in the same range.
I'm still gonna say that the only advantages Arima has is range and technology, but even then Levi still has the environment and speed advantage, especially in the forest. Still sticking to inconclusive until enough evidence is proven otherwise.