I figured it out a while ago based on rear wheel HP on a dyno and then HP loss at speed using a G-tech compition meter. It does look to be over .4 as mentioned. The usable HP at higher speeds has a huge loss from resistance. Over 120 or so mph it becomes a real challenge and even seems to require diffrent jeting there's so much load.
This is third gear with a few charts and assorted changes. It came out to be about 100 HP of energy loss around 110 mph. The faster you go the loss becomes exponential. The car on the dyno was making about 475 at the wheels when it made about 340 or 350 in motion of usable power.
Here's a formula.
http://www.gtechprosupport.com/support/AeroDragCalc.php