I own both cars and one is no better than the other,At the track I race at I run about the same lap times in the 19 turn class,in the stock class I'm faster with the Pro4 and I'm a bit faster in mod with the Xray,I race outdoor asphalt so stiff as a board is not allways best..
Both are good cars and just remember you still have to drive them.So for all you Xray guys, you can still get beat by a Pro4 if the Pro4's driver is better than you,And the same goes for the Pro4 drivers.It's all in what you want to Drive.