I'm still having a hard time understand why it would make the brake twice as powerful. Are you saying that a 35mm magura pad is going to have less stopping power than a 50mm pad? Becuase i was always under the impression that they create the same amount of friction (one as more serface area, but the other will (i'm not sure what the right word is) apply more push to the rim. I figured the differences would equal each other out so that it wouldn't make a difference on pad size. So i'm I wrong about that or right? I understand what you're saying about one 15mm piston would give you a ratio of 1:1, but having two 15mm pistons would give you a much bigger piston, but that would mean you'd have to move the leaver twice as much, so if you were to run two hope mono trials one one leaver, the leavers open system would correct that so that the leaver wouldn't be pulling twice as much, so if the leaver isn't pulling twice as much, the breaking power would be the same as running one. That's where i'm coming from, i'm not saying it's right though.