well...obviously because of the thin spot in the exhaust port it wasnt a "good" casting.
however, it just seemed like the shape of the core plugs for the left and right intake ports are different between the two, which is where i think the difference in flow came from.

i figured i'd post some out of the box #'s for the SR's to compare with:

lift----in/ex
.100--66.8/58.2
.200-131.7/105.4
.300-189.0/146.2
.400-238.0/175.6
.500-273.7/192.6
.550-284.9/198.6
.600-289.7/202.3
.650-291.3/205.9
.700-292.9/208.3

heres the BD numbers again:

lift-----#1I/#3I/#1E
.100--67.4/-68.0/55.7
.200-140.0/140.0/101.8
.300-203.7/206.1/141.8
.400-249.9/256.3/175.8
.450-270.7/278.7/187.9
.500-283.6/293.2/196.4
.550-281.2/291.9/204.9
.600-281.2/295.5/207.3
.650-286.6/297.3/208.5
.700-288.4/297.3/208.5

as you can see, even the weaker of the two intake ports is showing a nice gain in the mid-lifts compared to the SR.

the intake port short turn is shaped very much the same as a stage VI head(which also has good mid-lift numbers).

ive always found the SR intake short turn to be a bit of a challenge to get "right", and im hoping these new heads prove to be a little more "porter friendly"