The R&D Racing Pump Cover.. which is in part an adjustable leak jet, has worked for some people. I have one, but haven't been able to install it yet. I should have a report in a week or so.
As far as good looks... bikes always look great when they're ridden correctly. So practice practice practice..
But if you want bling... Some new shroud graffics will help. Check out One Industries, Factory Effex and N-Style for starters.
I really haven't done anything besides rejetting so far. Companies like Yoshimura will port your head, recut valve seats and do a few other odds and ends. Magazine writers seem to say that helps some bikes. But I really can't say how much it will do for a 250R. And those mods will cost you close to $2000. You might go with a different exhaust, but for the 250R, you could also drop a lot of cash on that. And the bang for the buck may not be what you are hoping for. The R isn't all that restricted to begin with.
One thing you may want to do to the bike is tune the suspension. If you weigh more than 150 lbs, that might make the bike better to ride and as a result, will allow you to ride it faster.
I know for a fact the forks on the 07 250R are harsh. Esp through braking bumps. Unless I sell the bike first, I'll be making some spring and valve changes to my suspension.
Good luck Tom.