Stud mounted are more stable since you're talking about a 3/8" or 7/16" stud versus the 5/16" bolt used with pedestals. Stud mounted are also infinitely adjustable (withing your geometry) which makes it tons easier and quicker to adjust the valvetrain. Pedestals are just the economical way of retrofitting roller rockers to a stock head.
I've run both and will NEVER go back to pedestal mounted rockers.
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Jeff Chambers
Trophy Stock #3
11.462 Seconds / 117.43 MPH
Chambers Racing Team