stock rods are usualy fine when resized with new arp rod bolts if ur staying below 6k rpms and 500hp.
u could go buy new rods but you may have to resize them also or at least make sure they are checked.
new rods is not a garanty that they are perfect, far from it sometimes, but at least they are new and not stressed in there earlyr life, something you might not no about the stock rods ?