The Yost kit is made for the H-D V-twin not the Blast always said just use the E-Tube and 175 is a yost jet is why it looks different it works.
An like Sytx have tried all different needle combos and springs and end up go back to stock needle it has a different profile then the V-twins for a reason it made to work with the single.

Shoot for the A/F setting Jet an Sytx are saying.