I purchased the 22mm ARB for my 1999 9-3. The difference was immediately apparent. It feels much stiffer on bends, and is even noticeable just changing lanes on the freeway. I definitely recommend this product. GS sent the item right away, and I could not be happier.
One note, When removing the stock ARB I broke the heads off 2 of the old bolts. Which ended up making installation a little more of a pain. Just be prepared to have the necessary tools available just in case this happens to you.

Rating: [5 of 5 Stars!]