While I love horsepower, I agree with Bob here.
I also had a 800 hp Paxton Gen III, and while it was fun and exciting, it was also very dangerous and often out of control. I am actually much faster road racing in my Gen IV with 620 hp than with the Paxton. I can remember driving through the traps at a Phoenix drag strip, and spinning the wheels due to the boost. Times were worse than now with my Gen IV as I could not control the traction variability as the boost went up and down.
SRT only has so much developmental time they can spend on their engines, and while peak hp is always good for bragging rights, they also must satisfy the noise, vibration, fuel economy, durability, cost, drivability, producability, and other parameters.
I know that Ralph and Winkles were tweaking the computer most of the way when they made their epic last minute calibration run from Florida to California. They ended up at Willow Springs Raceway, and put tons of laps on their pre-production car, getting those last minute data points before buttoning up the calibration.
Not sure how much more they could have done to optimize the Viper driving experience and HP numbers.
For many, they will say, just put on stickier tires, but that results in more things breaking and reliability going down. Then you need to beef up all the breaking things, and that makes the car heavier and more expensive.
I feel the the engineers have done a fine job with balancing out the engine, chassis, braking, drivability equation. The new Gen is quite the car, and for those who have driven it, it often exceeds expectations (but not always wishes).
Very few of the people compaining about a lack of hp numbers are up to getting everything out of the production Viper that it can offer.
In a like manner I was amused to see that Bugatti has revisited the HP ratings of their Veryon. The just went from +1,000 hp to +++1,000 hp. For many of us, there is never enough HP!