I see a few people running them. They advance the timing or something?

 

yes, they advance it about a degree or two, helps a bit with mpg, I ran one with my quad race box for a while till I got smart, got me a smarty and took off the roktech. simple little instalation, but as with most parts on the motor, a bit of a pain to get at. timing for teh quad box and the roktech gave a bit of a ratle to it, but not horrible.