The 2015+ WRX is a lot different (2.0L DIT, 6sp), but in 2011, there was a bigger gap between the WRX and STI. Numbers don't tell that story either, but there are a number of big differences that won't really show up until you're in the twisties. On the track, the Brembos alone make a big difference in shaving those lap times. the turbo size is actually the same on the WRX and STI in 2011, but the WRX has a smaller intercooler and 90 deg. exit from the turbo, limiting flow a bit, which you'll notice at the bottom as it doesn't spool up as fast. The 6th gear means more changing them, but also means putting down more power in each of them and a better selection (2,3,+4) for the important midrange band where all the power is. The 2015+ WRX all have 6sp and 5x114.3 hubs now. The 2015+ STIs have yaw control like Evos, which I really like and 6/4pot brembos (my APs are 6/4 also, though I have 2 piece rotors and SST lines too).