I have mentioned this before, but one of what I found as the most insightful performance books is "Think Fast", as the link says, it delves into the "why" more then the "what". Favorite quote on car set-up, "everything effects everything else"

http://www.goodreads.com/book/show/11985155-think-fast

also found on Amazon

Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.