The rage boost is only referenced as the catalyst for the SS2 form, so I advocate for just saying it's not 2x. It comes from one guide and has no manga support, unlike SS1.
I know where it's from, I'm just saying I disagree with the number.
Apparently the
translation is "
Trunks acquires a force 10 times greater, but his movement skills are more limited." It could be Grade 1 or 2.
Also, this was the guide that called SS2 the strongest form.
- Super Saiyan Grade Five (Strongest Form)
An aura with sparks like flashes of lightning and an upright, combative hairstyle are the distinguishing features of this, the strongest Saiyan warrior! One's personality also becomes aggressive; even the ordinarily gentle Gohan started to enjoy battle! Its power is enough to push back even Cell's energy bullet, which had enough force to blow away the Solar System!
- Son Gohan Gohan's true power that had lain dormant finally awakens! He transforms through his extreme rage towards Cell, who tormented Goku and the others with his Cell Juniors, and even destroyed No.16! His personality does an about-face; the strongest Super Saiyan, he easily battles Cell!