Definitely Extra Low is required... you can really feel the decrease in power when accelerating from standstill... However, when accelerating from a cruising speed, I do not feel too much of a difference. I actually went to the local Tesla store and tested their loaner Long Range 0-60 and it was the same story as my car. I emailed Zach Butler from Fast lane to provided him the link to this post. At the same time, I am wondering if Performance variants have to be in the extra low setting for suspension to achieve best acceleration?