Clearly those are awesome scores, Solaris! Congratulations.
Do keep in mind, however, that the grade equivalents are basically meaningless, particularly when you are talking about a grade level achievement test. What that 11th grade score means, is that your child scored as well as an 11th grade would if the 11th grader took that same 8th grade test, covering 8th grade material. This is not at all the same as saying that your child is actually at an 11th grade level of achievement.
Also remember that for all of these tests, you are comparing your child to an AVERAGE child of that grade, and that's a pretty low bar. That's why the talent search tests can be particularly valuable. With those, you also get percentiles to see how your child compares to other smart kids of the same age/grade level.
Even with all of those caveats, your DS is obviously "wicked smart," as many people here like to say.
