Hi, good question.
You want " a little more horsepower to the wheels" 'so you need to reduce friction and inertia losses from the drive line.
Carbon fibre tailshaft, thinner diff and gearbox oil come to mind.
But it's an odd question, most people want to make more power in general, and wouldn't you believe it, in the last 20 years some people have even done so with the particular car you own!
what are the chances of that!