Allow me to make a second comment here. I don't think you guys are seeing the big picture here. To some extent, the point of this manga is for Jun to learn to love being a gyaru, but how can he learn to love having big tits if he doesn't have big tits? I think that what's going to happen is that gyarukami's meddling is going to leave him a cup size bigger than before, and the girls at school are going to notice and be super wholesome and supportive about Jun's "growth," and that's going to cause a psychological change in Jun's mind where he begins to think of boobs as more than "just a burden."
At least, I sure hope that's what's gonna happen.