Good news on the shifter; it turns out all the drag is being caused by the very snug end seals – nearly five pounds of drag. Remove them and it works great, the shifter centering itself as it should. The seals however, must remain in some form since they’re the sole protection against dirt and water getting between the inner and outer sleeves. They were trimmed back to decrease the contact area but still retain a seal, and now all is well. Excellent, since it avoids a lot of extra work, and the exhaust manifold can be concentrated on.