My son took the SBV when he was 5y3m last fall. Unfortunately, I can't compare it for you to the WPPSI because I don't have any experience with that. I know that there are extended norms; I am currently waiting for Aimee Yermish to look at my son's raw scores and calculate his extended IQ because he ceilinged in four of the subtests (out of 10 total)... I don't know if it will modify his score much or not.
I have also heard that the SBV favors mathy kids, which my son deinitely is. That said, his score for the nonverbal was actually several point lower than his verbal. His FSIQ was the highest.
FWIW, my son really enjoyed taking the test. He wanted to keep going back to the "puzzle doctor". Good luck on the score. I wish we had access to a school where you need a 145 to get in!!
