[Keithc8]

Being that I do not even have headers for a 427 Cammer as I am sure most do not either, I borrowed a set from Jay Brown that he uses on his dyno. It was dynoed with open headers into our 5 inch exhaust pipes through our large mufflers.
Like most engines you would lose about 20 to 25 percent at the rerar tires depending on the headers, side pipes, mufflers and rear end in your car. This means that you could only have about 600 to 620 at the rear tires on a street car.
On a full race car that is worked out well you will get most all of it to the rear tires.

Thanks, Keith