I've had good luck using low tire pressures with Pirelli track tires. Super Corsas are good in this respect. Also the Metzler Comp-K slicks. They might use a stiffer sidewall for race tires. Low pressure in some of the tires I had was scary on the street. If the tires get hot enough, the air expands inside increasing the pressure. Speed also has an effect on the amount of flexion in a tire.
One whole inch is a lot. Did you need to move your wheel back a lot? Do you think one less link in the chain might be in order to keep stock wheelbase when lifting the tail this much?
What are Schnitz's links made of? Must be steel, hey? Not aluminum and definitely not Ti at that price.