I know these are adjustable but can they be adjusted to improve launch with stock springs i.e. 90/10 fronts 60/40 rears. If not what's a good shock/strut combo for street/strip duty?

 

I used 5 turns for the front and 6 for the back, cutting 1.5 60' the whole day.

 

That might work to some degree. But a front drag shock is a different animal compared to a road shock, with very low rebound resistance (lets the front suspension droop while the chassis moves up) and lots of bounce resistance to keep the chassis up. The Spec D's don't let you really do that combo as bounce and rebound resistance are increased or decreased with a turn of the adjuster.