Thanks @Phdv61slow on pick-up is due to to poor spool-up. With only one needle and Tillix ( or One needle - one dawes ), no matter what you do, you have to compromise on spool-up. One of the benefits of the multiple needles is to take control of spool-up, rate of opening of the vanes down low, and rate of opening in higher Revs (vs boost ) independently.
More degrees of freedom means... more freedom.
Would it be beneficial or easier to experiment by removing the tillix altogether and replacing with another needle valve?