Thous dyno # posted for the STI and WRX leave out one important factor.
The gear the pull was done in.
The WRX was most likely done in 3rd while the STI was done in 4th.
I have a seen a Cobalt SS S/C that has gearing vary close to the WRX do a pull in 3rd then do one in 4th not 15 min later and show a 35hp loss. Then do another 3rd gear pull and show almost the exact same #s it did on the first pull.
Later.