Can you scan and post your dyno graph? I want to see if it is bad or just the normal petering out. You can use a couple methods, VANOS on or off permanently and then play with timing to (usually bringing it down) to keep things from climbing past your allowable HP.
However, since HP is simply a function of torque and RPM, to keep HP flat after a certain point, TQ will have to fall (and maybe fall fast) as the RPM's rise.
