To a degree guys.

Lets use a stock 5.0 HO motor as an example.

Which headers will make the most HP with the best torque curve for drag racing purposes? This would be an essentially bone stock car with an off road exhaust.

Stock shorty headers with stock exhaust was used as the base line.

1 5/8 long tube headers with a 6" 2.5" diameter collector

1 5/8 long tube headers with a 10" 2.5" diameter collector

1 5/8 long tube headers with a 6" 3" diameter collector

1 5/8 long tube headers with a 12" 3" diameter collector

1 3/4 long tube headers with a 6" 3" diameter collector

1 3/4 long tube headers with a 12" 3" diameter collector

1 7/8 long tube headers with an 8" 3" diameter collector

1 7/8 long tube headers with a 12" 3" diameter collector

2" long tube headers with a 12" 4" diameter collector

I have a dyno chart here that shows the difference between each header.

Each headers had exhaust matching the collector diameter. That was the only difference in the tests. The same Borla mufflers were used in each test.

According to Brian and your theories,.. the 2" long tubes would offer the most HP and Torq. Do you agree with your theories or care to elaborate on why you chose a different header?

Hurst