i agree with grbrown, the stage 1 setup gives your motor an easier way to breathe, i.e. much less restriction in the air cleaner and in the mufflers or exhaust system. if the stage 1 download is similar to the big twins, it also lets the motor rev to 6200 rpm's rather than the stock 5500. just ask them at the harley shop, service department, they'll be able to give you a good rundown on what it involves and what the stage 1 download really does.

 

a little off topic but, I am learning about internal combustion engines now in a thermodynamics course- difficult but very interesting!