A control system for controlling the extent to which a valve selectively by-passes exhaust flow around one of two turbines in an engine exhaust system. The pistons are mounted in the fixed mold mounting plate in hydraulic cylinders and an increased clamping force is created for the platen clamping mechanism by an appropriate impingement of the piston. The implant configuration facilitates transforaminal insertion of the implant into a symmetric position about the midline of the spine so that a single implant provides balanced support to the spinal column. The sheet maintains its shape by woven or non-woven cloth having a hole in which the integrated circuit is buried.