A very smooth inner surface on the runners, can't be bad for flow.
Must say there are some very nice items coming out of ECC lately. You can be guranteed anything that gets released with big claims will be up to the job, they do have a very high spec GT to test it on, all well and good saying something but being able to back it up with a real test is what speaks a thousand words.
you guys done any aero flow tests on this design? built it in cad to find flow patterns and turbulence vortex's before constuction?
I've got a good aero package somewhere if I can find it when I was designing manifolds for our 3sgte drag setups, don't mind shooting a copy over if you have anyone anyone good at cad over there. very very good bit of kit and certainly makes sure its going to do what you want it to do. means you can tweek the design before you even build anyting. trying different plenum designs/runner setback, runner diameter/length/taper etc and throttlebody entry designs.
i find the varying lengths of the velocity stacks can help draw a smooth flow if there plenum chamber is slightly chaotic in flow, plenum end volume past the start and end stack can also play a part in this.