The above is not really accurate ...

First, not a good idea to "stretch" the spring. So, please don't try this and do so at your own risk. Secondly, the spring is a wear item and like any wear item after a zillion cycles, it becomes fatigued. The spring is designed for all applicable engine applications, not just "souped" engines, so that is likewise inaccurate. Third, and last, the "mod'd" aspect solely deals with the slightly enhanced pressure it creates. In no way does it "compensate" for other issues. Rather, your other engine's components should be working properly or correctly regardless, and this is just one piece of the puzzle.