Well, if it's GS300, then it has about 245HP, compare to 130i's 265HP (if I remembered it correctly), which means, I am not surprised if the two performed similarly.
One would have to drive GS350 to have a performance edge against 130i, even so, a "good", "courageous" or "crazy" 130i driver could still keep up. After all, there are so many factors on the road, just a slight performance edge can easily be negated.