I think you are misunderstanding what it takes to go fats top end. To acceive top end speed you do need power but more importantly you need a decently heavy car with low gearing and good aerodynamics. A lighter car with more horsepower means it will accelerate faster but not nessecarliy mean it will go faster in the long run. It all depends on what the car is buit for. Back on topic I do think and SVX can reach a speed of 170 mph.......
Going downhill with a tailwind of 30+mph in 40* weather
Tom