RHARVEY-
Pretty much on its face at a little past 27. Good up to 26 or so then starts cutting off. This is with a stock plate though, haven't been much over 68mph with the #10, so I can't compare it yet that way. Doesn't matter to me though. Rarely pull anything at highway speed since most of it is farm equipment. Even on the interstate, I RARELY go over 70mph, so the RPM aren't that high anyhow.
DSiemens-
The chart doesn't necessarily mean a whole lot. That is mostly for a plate in stock position. Slide the plate forward, and you can get more power out of it. Slide it in an auto (180hp) truck, and you could probably (un-educated guess) get another 30hp (?) out of it if everything else is stock.