Unexpected poor handling with Konis

I ran my first event of the season yesterday with my newly-installed Konis and the results were poor. I'm now trying to figure out what to do next.

Setup: 2014 ST with Dirizza ZII 225/45-16 on OZ wheels. Porterfield R4S brake pads. Koni yellows front and rear.

1st run: Shocks full stiff rear, 1/2 turn from soft front. 38 psi front/42 rear.

Car was all over the place, I could not keep the rear end planted. All I can do to make it through the course with just one cone. 3 seconds behind Des in his ST.

2nd run: Shocks the same, pressures 38/38.

Much better to begin with but still eager to rotate. Entered a fast three-cone slalom with a short braking area into a right-hander. Car snap spun on me and sent me off course into the grass and a side taxiway. Day over per our 4-wheels-off rule with a DSQ on the score sheet.

From my perspective the common wisdom of Koni shock settings is way off. I'm thinking the middle setting rear and half-way to 3/4 front. Am I right and everyone else is wrong or did we goof up our install some way?

Des does have a Cobb front bar but that doesn't explain the 4 second difference between us. I road with Des and his car had very good turn-in but tended to loose grip in hard sweepers. My goal is the best of both worlds, high grip with good turn-in. I think it's doable, it's just figuring out how...