Engine torque doesn't change. It is the torque that is put to the ground that changes. Your transmission is basically a torque converter.
You're engine is making 279lbft peak just now. On assumption that you are running a 3.9 Final Drive, you would actually be putting down 1347lbft peak to the ground.
i.e 1.238 (4th) x 3.9 (FD) x 279lbft = 1347lbft to the ground.
0.972 (stock 4th) x 3.9 (FD) x 354lbft = 1341lbft to the ground.
Put it this way, a stock WRX only has 217lbft engine torque. If the engine to ground ratio was only 1:1 (as a dyno will show), you could have several friends push your car faster than the car could accelerate.