Jeff, the ones that PAC sells are the best ones out there. I have tested Comp and PSI beehives. These are lighter, taller, and give me the pressure I want. They last too. I have a set with over 130 runs on them and they haven't changed 5 lbs seat. I set up at 180lbs and aboout 390 over the nose. We punish them pretty regularly and I know John Duzac does the same with his 302 Z.
If anyone wants to see some first hand, I have an extra head with some different springs set up for comparison and a spring checker. We will be at Joliet Nats and points meet.
Check out this link.
http://www.pacracing.com/Beehive_Spr...Set_of_16.html