Shackle angle?

Those springs will settle a bit especially the more you romp off the launch pad, mine were the same as yours at first.

You can remove the rear spring clamps which will let the springs expand and settle in quicker wich will plant the springs better for hard launches but you may compromise sis by side spring integrity upon cornering.

Did you torque you U bolts properly?
The manual says 45 lb/ft but I like to go a little snugger than that.

Too tight can cause thumping or hopping and possibly distort the axle tubes.

Too loose can cause all kinds of problems.