Just passing along some unverified info on my part; I was going to buy billet rails on ebay a few months ago, and emailed the seller with questions about them. Turns out he runs a Mustang speedshop, and he said that he's tested stock rails to well over 600HP with no problems whatsoever, and he literally told me flat out not to buy his rails because they were a waste on my bolt on 302. Maybe he doesn't know what he's talking about, but I'd think as a seller he'd be trying to talk me into it not out of it, if it wouldn't hurt anything to have them. Whatever, I'm going with all Aeromotive stuff now anyway so I'm glad I didn't do it.