A fuel injection system for an internal combustion engine includes a fuel injector pocket, formed within a cylinder head, for housing an injector which sprays fuel into a combustion chamber defined by the cylinder head and a piston crown. The injector is mounted with an isolator which is loaded at a lower, elastic rate during lower power operation, with the elastic load element being stacked solid and subject to higher rate column loading during high power operation of the engine and injection system. The isolator controls unwanted injector ticking noise, while protecting the integrity of the injector's tip seal.