They have certainly as of late waited to release numbers, though they gave an est. and they also stated cars in which it will have a better power to weight ratio then.
In my honest opinion, it isn't the 1960s where the most important number for a car was it's horsepower. Now days the more important number especially for a sports car is increasingly it's lap times. While the horsepower rating still has merit in on internet forums I do think that people would be more impress with a car that has less horsepower and yet turns faster lap times. For example the C6 Z06 (with all of the go fast goodies) post faster lap times on some tracks then the ZR1 Corvette (also with all of the goodies).
Though I wouldn't be shocked if GM was spacing out launches and information release to give all of the products this year it's own time.
For me, the simple fact that the Z51 C7 is running competitive lap times to the Z06 is more then enough to amaze me. Considering the price of the C6 Z06 and it's engine, brakes, wider tires etc....it is like a Miata keeping up with a base C6.