Ford 4R44E, 4R55E, & 5R55E Boost Valve & Sleeve This Steel Series replacement boost valve & sleeve kit gives you a perfectly dialed in ratio, slightly higher than the stock valve. This new valve helps eliminate all the problems associated with a worn out stock aluminum valve such as low line pressure, softer shifts and cross leaks. As with all Superior boost valves, this valve is made out of 100% hardened steel & made in the U.S.A.