The garage rocket revolution
bitoflife.mkronline.com
bitoflife.mkronline.com
My thought is that any better performance will cause them to start to run afoul of various 3-letter agencies. Any better guidance systems will cause the US government to suppress them fairly quickly, as they'll be intruding on (1) the defence contractor's monopoly on flying fast, and (2) the government monopoly on shooting down flying things.
It's a running gag in the various Star Trek series that people learn how to build warp drives (and other very advanced things) in high school.
Paraphrasing a time travel episode: "in my time [the future] there's a [technobabble] in every desk."