Not many people care about speed, unless you drive on the Autobahn with no cars around or want to risk a trip to the local clanger. But you need loads of power if you want to accelerate quick. So about 800HP should be fine with the current weight, or alternatively less when we can do a 0-60 in 2.5 secs. Any quicker and we would need a stronger car and G-suit to handle the G Force and impending tunnel vision . But of course we only accelerate to the speed limit then we back if off a tad.