not worth the hassle, as recommended sell your car and buy a 1.8T. If that's not fast enough then chip it !
You could doubtless spend thousands in modifying your 2 litre GTI, but why bother as the 1.8T already has better suspension, brakes and interior equipment. You will never see a return on your investment in modifying the 2.0, as it will be harder to sell and more expensive to insure, less reliable etc.....