au rear live axle SL suspension bottom out

[ben131185]

I've got SL king springs all round on my live axel au.
Rear sits slightly lower than the front.

Sometimes when travelling over speed humps or over bumps on the freeway the rear suspension seems to bottom out. It become more noticable after the lpg tank went in.

Has anyone else had this problem?

I still have the stock shocks in the rear, maybe its them that are bottoming out?