Seems that Blox and a few other companies have manufactured similar products for half the price if not less. I'm contemplating doing a full write up on them this summer when i'm out at the track. It would involve a comparison test. I would run the first day without them, install that night at the track, then see what difference they made the following day.
Only real issue is ensuring that my alignment is the same, which would probably take more time than installing the parts! Might be something fun to do though.