GL 1303S project from Romania

[Jim]

Check how low is the rear suspension and if the bumpstop hits the upper end of the body.

If this happen then it should give you this extra 1-2 bounces.

I agree with Wally's thought, bilsteins + 23.5 944 torsions are one of the best choices!

[Wally]

+1 on shortening of the bump stops after lowering. Didn't think about that one, but it sure sounds like the cause of your problem.