Race school vs HPDE ... very different things with different goals. At a proper race shcool, they will teach you race craft, and will push you much harder. Also, the SoloSprint school (aka, Ontario Time Attack) is a much more balls to the walls school experience as the entire point of SoloSprint is you vs the clock.
Listen to people who are faster than you ... let them drive your car to show you what's possible. You WILL get faster from that, trust me.
But in the end, the only thing that will make you faster is bigger balls and ignoring your life preservation insticts