Duane, no car is the same. I know stock TTs who can almost keep up with a GT2, no kidding. Our other Editor-In-Chief CR testdrove a TT from the factory and was very surprised to see how fast this car was.
Let me give you an example: We testdrove the 996 Turbo compared to the GT2 and from 0-80 mph, the difference was almost non-existant. Over 100 mph, there was a clear difference and at around 125 mph, the GT2 already drove away. The GT2 is around 100 kg lighter than the 996 Turbo.
The X50 isn't basically a GT2 engine, the GT2 engine is basically a Turbo engine.
The GT2 engine has just different turbo chargers, exhaust system (incl. cats), intercoolers and an additional oil pump. The X50 engine lacks to my knowledge the additional oil pump and the gearbox is just an ordinary TT gearbox with a shorter 6th gear without an oil cooler.
Do you have the official X50 performance data from Porsche ? Tell me the differences between X50 and stock Turbo.
Regarding Roock and other Tuners: the power claims aren't always what it should be and I guess many people already realized that.
Don't get me wrong: I still believe that X50 is a good option if you want to have an original Porsche car and don't want to worry about warranty issues or reliability.
But performancewise, it isn't even near the GT2, especially at speeds below 125 mph.