I think that we're going mostly by personal experience. I know that each application is different and no 2 engines are a like. But, at one time I did have a dyno sheet showing the power gain from advancing the ignition timing and it was a lot more than 7 horsepower. There's so many other benefactors that can / will affect final power numbers. Also I failed to mention that I was talking about flywheel horsepower. I wasn't trying to sound like a know it all, just going by what I've seen from helping others with their cars. I still got a lot to learn
