Well see here's the thing.....a "performance" curve includes "some way" to limit total mechanical timing. You cannot do that with sprAngs. Don Gould has the only way I know of with the FBO limiter plate. 8* is well within a stock HP range. Not so good with long durations and tight lobe centers. All springs do is change what RPM the advance maxes out. They don't limit the advance. You need to limit it for a true HP curve for a true HP engine with more compression and lots of duration. Big duration cams always want more initial. Cranking up initial without a limiter on the mechanical makes for too much total.