It made a remarkable difference for me over 130mph. In fact, I wouldn't go over 137 without it (referring to a specific instance). Granted, my tires weren't the greatest at the time (plenty of tread, but a weak sidewall that expanded, lifting the front of the car) and bad front struts to boot.

But by itself, it did give greater stability at high speeds. Normal operation, it'* designed to maximize airflow through the cooling system and engine bay.

Yeah..no salt flats or race track here for me to hit those speeds.

Whose?

I ran for years w/o one. Never missed it.