In order to use rockers you would have to mil down the valve guides since you are running a cam already. I would go for at least 42s if not 60s just to give a little more headroom in case you decide to go further. I would go for the 304 stainless off road pipe with the 3" outlet and mate it to ZZPs 3" stainless catback.
And as Fordman stated read over this thread http://www.grandprixforums.net/threa...00-Powered-Car!!