I hated them at first. Lol they was a ***** to get shimed up right. Not a lot of room with 3/8th push rods and trickflows oval push rod holes in the head. But a lot of that could of been the installers ( me) fault. But so far 12 7000 RPM passes latter, I havent had any problems yet. Also I am useing one of mikes at B3 racing rocker correction kits.