You don't have to have one, we went just as fast before they were even made, as we do now with the girdles, but I do have them on a couple of engines now. How many people think a stock 440 steel crank won't go in the 8's in a 10" tire car @ 3300lbs with 300hp of nitrous. Just like most of you say stock blocks won't last going that fast but a few of us do it all the time with no problems.