Thats actually a very good increase in speed for relatively little in terms of mods:
At higher speeds aerodynamic forces become important, increasing as the square of the airspeed. A flat plate of one square foot area and perpendicular to the relative wind will produce drag force of zero at zero miles per hour, 33 pounds at 100 mph, 133 pounds at 200 mph and 299 pounds at 300 mph. The corresponding horsepower required to overcome the aerodynamic drag is zero, 9 hp at 100 mph, 71 hp at 200 mph, and 239 hp at 300 mph. A drag racer may have drag equivalent to a flat plate 12 feet in area and acting several feet above the ground, requiring 2,868 hp to overcome the aerodynamic drag at 300 mph.
Going faster is expensive, how fast do you want to go?