more y8 intake

been working on this intake all the day. i recovered only 3.5% of airflow, with port matched throttlebody. i guess i can't get more cfm on this,so i'm going to close and weld it.
despite d16z6 intake  flowed more, the bigger plenum of y8 benefits high rpm or turbo applications. the reason that z6 flowed more,is in its larger runner, about 20mm more.   we calculate flow with the following formula   cfm= velocity * area.  area o a pipe is calculated by  A= D *3.14* L.
diammeter of both pipes are the same, so a larger runner increases the flow, but there is a problem with the inrceased lenght of the runner in case we want to exchange runners each other. the harmonics.
usually we seek the third harmonic which give us more torque, extending the the runner maybe we lose the optimum lenght to use third harmonic. i have to calculate this for a engine reving up to 7500rpm.
a picture of both intakes.