[Fot] How likely is cracking a trailing arm on a TR6?

[sherry robyn]

I have regular height stiffer springs, rear sway bar, stock soft bushings in
trailing arm and diff (with cups on diff mounts), frame strengthening in
certain areas, and red Konis (soft bushings) with the conversion tied into the
roll cage.  I currently have the Konis set on the second to the stiffest
setting.  I backed off the stiffest setting for the Konis due to talk of the
trailing arm cracking.  I am just wondering if I can go to the stiffest
setting on the Konis without much worry.  Any thoughts would be appreciated. 
Thanks, Jim