[Jeph]

By faster, do you mean top speed?
Or do you mean around a track -like an autocross?

If you're not referring to top speed, I would be willing to bet any difference would not be noticed by a human.

Some people think it makes the car more rigid, but it seems a little too flimsy in the joints to make a difference in rigidity.

I've autocrossed with and without the hard top. However my skill prohibits consistancy that would result in any conclusive evidence. (I think I did better with the top off.)