The stock header pipe is about 30". Many tests made by several groups confirm this length as being very nearly the best for all-round performance. Shorter (less than 27") and longer (over 32") header pipes significantly reduce peak power output, throttle response and over-all performance in general. An exception to this "rule" are a couple of the high performance 2-into-1 systems which work very well with longer (and un-even) header pipe lengths. Stock Harley header pipes are near-perfect in diameter and length.

I would agree with this as far as stock heads and cams go, but with the heads made to flow { welding and porting with larger valves, or replaced with S&S or other High performance heads} and more aggressive cams. A stepped header starting with 1 7/8" ID and increasing in diameter 1/8" every 10 - 12 inches with an overall length of 36 -40 inches per pipe has proven to have the broadest torque curve without hurting top end HP.

I agree with you there too.
This was meant a basic all around statement dealing with basically stock components but you are correct and on the ball too.:hii

I agree with you there too.
This was meant a basic all around statement dealing with basically stock components but you are correct and on the ball too.:hii
Glad to be here :D