Choosing a manifold depends on your needs and what you are willing to compromise. RevHard makes an excellent ductile iron cast manifold that will not crack. All tubulars are prone to cracking eventually, one of the keys to keeping your manifold and turbine housing from cracking is to support the downpipe at the flex-joint at the stock fulcrum point. This way when you drag-launch the car, all of the force is not put on the manifold and turbo, ofcourse if you race with an open downpipe it's not that huge of an issue.