How far were they from coilbind, just because they werent coilbinding dont mean they are setup correct. Your springs should have a tolerance as how far from coilbind they should be @ full lift, mine are around 80 thousandths from coil bind and they took several shims to get there, I run the PAC springs and over .950 lift and 9000+ rpm, if they arent setup right you could be having spring surge.