twin scoll manifold wastegate question!

[Shane@DBPerformance]

FP Black Evo 9, stock ported exhaust manifold. Internal and external wastegate. External used for final boost level. Internal used to retain twin scroll until 20+ psi. Once the internal opens, the exhaust merges for a few inches to the external. The laggier run is with the internal wastegate arm unhooked and the flapper open to the external the whole time. With the factory Evo twin scroll and internal gate, the exhaust does not mix until the wastegate opens.