Reason they only pushed it to 6500 is because it started to loose power after that, so it's pointless pushing it further.
What you want from a graph is the curves to be as smooth as possible, and for them to be on the increase for as long as possible, and on the decrease for a little as possible. Look at mine. 6500 to 7100 it's flat on the HP curve, no drop off at all which is great.
Now look at yours. 6000 it peaks and then gradually drops off until 6500, at which point the dyno operator stopped the run.
Now look at the flatter torque curve. On mine it's pretty flat all the way, yours has a spike at 3600. Mine steadily drops off from 6500 to 7100, where as yours will fall quickly from about 6000-6500, in conjunction with the HP curve.
The aim is to extend the power for as long as possible, and hold it for as long as possible, without letting it drop off.
You can smooth it out with regular services and maintenance. I change my oil and filter every 6 months/5000 miles, plugs every 8 months or so and distributor cap and rotor every year. As well as cleaning out air filter every so often along with throttle body.
