So a little more torque. You could do a bunch of things. Testing new pilot jets, adding a spacer between the carb and intake, higher idle speed, believe it or not, the clutch. The clutch on my CR250 was adjusted so close to the bar that it flew off the line. Holeshot monster, but I had to hold the front brake when I was standing still to keep it from rolling. When you do certain things, you lose others. More low end sometimes means less top end. Make sure your bike is tuned tip-top before doing anything. Just making sure the carbs are properly synched really helps. If the bike is not perfect to begin with, then more problems will occur.
That's like street/strip cars. They look really cool and really loud, but have no top end. They're great for the track, but suck on the real roads.
As Tonyc said too, gears. Different sprocket sizes. Again, you'd lose some top end.