There was a good thread on Speedtalk a while back:
1 5/8” headers and 500hp? - Don Terrill’s Speed-Talk
This quote was interesting:
"Chris at C & S Performance "radically detuned" our best / fastest SBC442cid that made 816 HP @ 8200-8300 RPM
to around 670's to 680's HP with 1 5/8ths Headers + less Cam , i think less Comp Ratio , Carb CFM "
He later states its 640 HP
