With APR stage 2 software you still need to make sure the dealer has flashed the test pipes file or you will get the warning light on for catalyst efficiency code P0420.
If that's the code you have the car will run perfectly normal until you get the proper file loaded(assuming the car has no problems)
Best thing to do would be contact Evan at APR and with your vin number he will be able to tell you which file you have on your car.
He's very helpful so well worth the call.
As for bhp arguments and people saying 305-310 bhp is only achievable this thread has shown and proved that software has moved on a long way and achieving even better results.
Keep it up guys.