People have had inconsistent results with the braces, although I put all of 'em in my car (front frame, front connecting, front fender and rear seat), and they seemed to help a bit. *MOST* of the squeeks and rattles went away, but the covers for the T-top latch mechanisms still chatter a little over hard bumps, but that's not the fault of the braces.
In an 11 sec. car you will need a bar to race legally anyway, so that may be your best bet.
Try doing a search for 'rollbar', you can find a lot of good info. Seems like some bar installers are hackers, and some are true craftsmen. Don't take a chance with your GN, go to a reputable shop and have it bent the way you want it.
Good luck,
Steve