I've heard that the College Board investigates score improvements on the SAT if they're extreme enough because it raises questions about whether the student cheated. How much would your score have to improve for this to happen? Is there a specific benchmark?
There is mixed information on this question. Because scores may be under review for different reasons, it's hard to tell what the threshold is for a suspicious improvement. On the old SAT, it seems like it may have been between a 300 and 500 point improvement overall. It's pretty clear that any score that showed an improvement of over 500 points was investigated by the College Board. If we convert this to fit the scoring model of the new SAT, you could estimate that an improvement of 300+ points overall from one test to another would trigger an investigation.
This doesn't mean your scores will be automatically cancelled. It just means the College Board will look into them. If they find there is reason to suspect you of cheating, you will be given an opportunity to either retake the test or prove that your score is valid with evidence (this might include showing that you participated in an intensive prep program and/or sending a high school transcript that demonstrates your academic ability).