What happened to beehive springs?

I don't know about all that. About 8 years ago I put a Hughes solid cam in my 340. Couldn't get that thing to rev over 6700. Chased my *** for a few races trying to figure out why as my old cam turned 7000 easily. Talked to Dave Hughes, he told me it was likely valve train stability. Recommended running beehive springs at 145# seat pressure, so i tried them. Motor now turned clean to 7300 on a gear change. Car went from 11.60s at 113 to 11.40s at 115. Have had similar scenarios play out on other motors in the shop.