im pretty sure its not the rockers that you are hearing but the added pressure of the valve springs closing. doing any sort of upgrading on an ls1 like larger valve springs (higher pounds) or higher ratio rockers make that clicking sound. its really nothing to be worried about and to be totally honest, you will have less side load of the rockers plus the correct valvetrain geometry with the stock moddified rockers and are much stronger then any roller rocker setup. the problem with roller rockers is that as the roller tip "rolls" across the tip of the valve when it starts to open it actually starts to roll from the center of the valve tip to the outside of it causing side load and premature failure of the valve guide. with stock rockers, the rocker tip stays put on the center of the valve stem. on a ls, the norm for hp gains with roller rockers is so minimul that it doesnt warrant the cost and by minimul i mean about 5 whp or less. alot of guys go with the slp 1.85 ratio rockers which are like these stock modified ones but modified from 1.7 to 1.85.
