what do you mean by stage I? high flow air filter and pipes? you gotta have some kinda fuel manager on there or your done for. whether thundermax, power command, or sert. thats only if you messed with the air cleaner
If you have the stage 1 down load from HD your bike will run with in specs. The real advantages of a PCIII or equivelant is the reduced heat, better running motor. You can also expect HP and TQ gains of about 10% which is alot for a bike.