So as you have said in your other thread, you have done everything but the most crucial thing. ECU!!
You can't expect the stock ECU to understand what is going on and hence why it is running like crap. I ran my GT-RS on the stock ECU for a while before I got it tuned so I know what it is like.
So ECU and Injector upgrade time, put some boost into it and you will be amazed at the transformation.
And yes the GT-RS does whistle a lot but they tend to whistle a lot more when they are new. The reason it is sounding so loud is all you can hear is the whistling when you put your foot down, but the car aint going anywhere due to the stock ECU. With a proper ECU and a tune you won't hear the whistling as much over the engine noise.