<p>Obviously, since you don't understand that there is no statistical difference between an 800 and a 790, you don't deserve an 800 on a math subject test.</p>
<p>The general rule of thumb is...if you score 770-780+, don't retake. Really, anyone who is scoring 770+ should be able to score a 800 if the questions were "in their favor."</p>
<p>Why would a 790 make any difference from an 800? And plus engineering schools probably get a billion kajillion kids with perfect 800s anyway so even if you had gotten an 800 it might not have made a difference. You got an excellent score, leave it alone.</p>