BYU in Big 12 play has gone against the #8, 12, 14, 15, and 16th defenses in ppg
I think our offense has really grown over the course of the season, but they've been feasting on the defensive dregs of the Big 12 conference, while Utah's defense is ranked slightly better than SMU's.
Barring a collapse by Utah, I would expect BYU to score closer to 20 points than 30 points. I don't think scoring over 20 points is a given against Utah's defense, especially at RES.