Buruma: (She brings up schematics for the Bruits wave emitter.) Once we use this Bruits wave emitter, surpassing even Super Saiyajin 4 will no longer be a dream.
Vegeta: Surpass Super Saiyajin 4?! Buruma, when will you have it completed?
Buruma: Before the Earth is destroyed.
Vegeta: Nice work! (He crushes the canned drink in his hand.) Kakarotto, bring on your Super Saiyajin 4, or 5, or whatever you want! I'm still not finished!
Buruma: You sure are a battle-loving Saiyajin! But then, I'm still that Saiyajin's wife. (She winks.)
Vegeta: (Cue epic blushing.)
This seems to imply that, via ample exposure to large quantities of Bruits waves, not only could Vegeta reach Super Saiyajin 4, proven true in episode 59, but, provided he is exposed to further and larger quantities of Bruits waves, he could also break through the "barrier" of Super Saiyajin 4, similar to how he, Trunks, and Gokū reached the advanced Super Saiyajin 1 states, or how he, Gokū, and Gohan all reached Super Saiyajin 2.
Might this result in advanced forms of Super Saiyajin 4, creating bulked up and more powerful red-furred, black-haired states, or possibly a potential, completely separate 'Super Saiyajin 5'?
I personally would have liked to have seen something after or during GT's conclusion, an OVA, perhaps, that takes place after Gokū's departure but before the 100-year time skip, in which Vegeta, stepping up to succeed Gokū as Earth's champion defender, makes use of a rebuilt Bruits wave emitter to reach Super Saiyajin 4 once more, and, the form's power proving insufficient to take on some new villain, orders Buruma to flood his body with more Bruits waves, disregarding potential negative effects that his body might sustain as a result, in order to reach a level above or beyond Super Saiyajin 4.
Of course, GT didn't run long enough or reach a story point at which this might have happened, but I thought it might be fun/interesting to discuss what interested folks' opinions on the matter might be. What do you make of this exchange between Buruma and Vegeta, and potential forms beyond Super Saiyajin 4, had GT continued? Thoughts? Ideas?
For a few examples, here are MalikDBNA's "1st Ascended Super Saiyajin 4", "2nd Ascended Super Saiyajin 4", and "Super Saiyajin 5" forms.