ET with and without wheelie.

[JGrossijr]

No 2 cars are exactly the same so it's unlikely there is a "right" answer that fits every application. In my experience as long as you're not unloading the rear tires, it's not the wheelie that slows a car down, it's the landing. I have found that if I can smooth out the G-meter dip at touch down, without giving up any 60', the car goes faster. There are lots of different ways to approach that, including wheel stand height.