1st and 2nd gear don't make as much boost as the rest on a stock car, the ECU limits it to a lower peak. At least that's true on the WRX, I'm assuming the STi is the same. Boost also tapers at the top end of the rpm range. A 2nd gear pull up a hill won't tell you what your max boost is, it will tell you what your max boost in 2nd gear up that hill is.
