Does Goku's SSj4 form get any stronger?

[Diamond Ryan]

Is SSj4 like any other form in that it grows at the same rate as the base of its user? Or is it more of a potential unlock that puts its user at a set level?

Personally, I'm more inclined to think of it as the latter, as it makes stuff like SSj Goku doing better than every other fighter vs Super 17 easier to rationalize, as you could say power from his SSj4 form began to bleed into his regular forms.

 

[Captain Cadaver]

As you mentioned, potential unlock of sorts makes the most sense when the Perfect Files describe it as bringing a Saiyan's power to their utmost limits and the only scenes in which it's confirmed to become stronger are ones in which Goku had external factors to increase his power with the Saiyans allowing him to access SS4's full power in the Baby Arc and then bring him beyond his limits in the Evil Dragons Arc. That, and how his base and SSJ forms seemed to constantly be getting boosted tremendously from the Super #17 Arc until the battle with Si Xing Long.

 

[Papasmurf]

It's stated by the narrator that the Golden Oozaru transformation unlocked Galu's hidden powers, and SSJ4 is stated to be a form that brings a Saiyan to his utmost limits in the Perfect Files. While it's not as clearly explained as SSJG's power bleeding into Galu and Vegeta's lower forms in BoG/FnF/Super, the unlocking of potential bringing GT Galu's lower forms to a higher level makes sense with him being stronger than Oob in SSJ against Super 17.

 

[Let's Go Fearless!]

Nope, it's the reason why the other half Saiyans have to share their power to Goku.