I can't say how much of the gain was from the headers and how much was from the carb main body. My guess is that at least 80% of the gain is from the headers.
You changed the main body on the carb, so how much more air and fuel are you getting compared to the Holley? That will make a difference right there. It just like changing to bigger jets and installing a larger venturi diameter. Your motor may have needed the different fuel and air ratio with the cnc ported heads. I can not see anywhere close to an 80% gain. I run a .030 over 440 with 10.5 compression with an Edelbrock RPM cam and heads, with a Quick fuel 850 with Schumacher headers and still run 11.50s@117mph. Your test should have been done before you changed anything.
