Not many engines can have flat plane cranks by the looks of it
only L4 and v8 engines but not v12 as they act like an L6
The balancing tube should cancel out any reversion that could
interfere with the setup but will be interesting to see results.

For webers single or doubles the manifolds are not optimum
for all applications where different lengths could improve
those after street tunes but most weber manis are designed
to fit into the engine bay.

However by tinkering I found the longer than length of the
runners the fatter torque that I could get for the street.
I used to make my own quad cv carb manifolds of varying lengths
and the longer I made them thanks to 1000 having good space
for them the better response I had everywhere.