Now that my US 6 speed is broken in I'm happier with stock than expected. The context is the car's for sure peppier than our Outback, smaller, and the Sienna SE is rated 292 HP. The stock Alltrack sips less fuel than the others. Thus, some wait and see.
If I do more travel with the roof box or two bikes on hitch rack I could change my mind. I guess I'm old and responsible because I don't want more power in the way I enjoyed my Mustang GTs. My Alltrack will for the most part shuttle one person and work items or 2-3 of the family of 5.