C16 needs alot of timing.
The 16g drops off so bad up top that you can get away with alot of timing on C16.
I dont disbelieve the numbers. When I hit 414hp I was so happy to have done something no had done yet that I packed it in right there and let Joe get on the dyno.
There was still more there as I found after further tuning at the track.
The trick is not just in tuning but in making sure all your parts are working together and not fighting each other. Lets also remember you can put your car on 3 diferent dynos and you will gat a diferent number on all of them.
But Curt has backed up his dyno numbers with more than impressive et`s every time. Curt is a good guy and has never done anything to make me think he would exagerate or post a dyno number he didnt believe in.
Also most good tuners are not going to reveal all thier little tuning secrets.
I will say this though.
There is a lot of hp to be found in learning how to get you a/f and timing working together through the whole power band for that magical number.