by my unerstanding, timing doesn't necessarily equal power. it just makes sure all your fuel combusts at TDC. you have to spark the fuel earlier when the piston's moving faster, and i guess at lower rpm's there's less pressure, meaning it would take longer for the fuel to burn. so if you run boost, you can spark it later since it's pressurized and it'll burn quicker. we're also talking about degrees of timing, i bet if you look at time in seconds between the the spark and TDC it would be roughly the same.
or i'm way off and talking out of my ass
