Given that your car is relatively new, I would guess it's one of two things:
1) Fuel injector jets might be a little clogged. Do you run a bottle of cleaner through the fuel system every 3,000 miles or so? If not, I recommend it.
2) Air filter might be dirty. Simple to change.
When you stomp on the pedal and don't get the turbo boost you experienced when the car was new, it's probably a fuel/oxygen ratio issue. Try the simple and inexpensive trouble-shooting first. If the problem persists after the two ideas above, then maybe something more serious is wrong with a sensor somewhere. Your car is still under OEM warranty, so it's shouldn't drain much of your wallet.