I have a guy who brings his saw for service & his chains sharpened ,he is an electronics geek in his daytime job, he built a test rig to plot the advance curve on saw coils the local Stihl dealer lent him half dozen of the same model new coils. No 2 showed the same advance curve. 1 produced the correct advance curve related to that model of coil ,2 produced .5 of a degree more advance over the curve 1,1degree of advance, & 2 produced .75 & 1 degree less advance than should have so this would point to different performance with advance of timing & it suggests a suck it & see in regard to the advance amount Please don't ask me any questions regarding this as it is around 15ft above my head I' m more a hammer & chisel man but none the less it was an interesting exercise