Stage 1 is the way to go for what you want, but drilling out the baffles on a Delphi bike is NOT a good idea. Cheap slip-ons like Cycle Shacks work very well. A couple hundred extra but you will be much happier with the sound and the performance.
On most Delphi bikes the system will compensate for slip-ons only, so if money is the overwhelming consideration you will probably be better off just with slip-ons. You will have sound and a very moderate performance increase, and you can get the intake kit and reflash later to get another bit of power.
On most Delphi bikes the system will compensate for slip-ons only, so if money is the overwhelming consideration you will probably be better off just with slip-ons. You will have sound and a very moderate performance increase, and you can get the intake kit and reflash later to get another bit of power.