This is not speed-build rig! I have had sportscars for 20 years before I bought Pathy. Now I am so happy roaring down the highway slower and safer than most of others.
But in general, to gain TOP speed, you would need to modify gearing, I think transfer case is the target for re-gearing. Change gear ratio and you gain speed.
...but you will loose startup acceleration and torque in LOW mode. Also, you will move faster, meaning you should also STOP more reliably, so to be responsible, you'd need to upgrade your brakes, too. And do not forget higher speed rated tires.
All in all, buy some other vehicle to make it go faster. That's my 5 cents
