3-5 degrees down for track. 5-7 down for street. The straighter the line the less angle bind. But also more rotating vibration. It's why street should have more. But with today's caltechs or 4 link systems? What ever the manufacturer recommends. Which I believe is not that much different? I would start on high side. If both track and street?
Why would a person want 5-7 down " more angle" on a street car that aint gonna twist the rear as much as a well biting dragstrip set up ? Would be running 5-7 out of line all the time - Goes against everything I `ve ever done , or heard !!