Stage 1 - Really isn't a jet kit. The kit only includes different needles to richen up the air fuel mixture.
Typically people do the stage 1 kit when they are changing to aftermarket higher flowing exhaust pipes,
and are keeping the stock air filters and air boxes. Below is a picture of what the needles look like.

Needles - The needles are cut for a steeper taper and allow more fuel in. The stock Marauders come from the factory running very lean and changing exhaust pipes or air filters will make them run extremely lean, and could possibly cause damage. Although some have reported that a few exhaust pipes such as the cobra slashcuts run fine without installing a jet kit.

Fuel Mixture Screw (aka idle air mixture screw, one on each carb) - Allows the tweaking of the fuel mixture during idle, and must be done with a stage 1, 2 or 3 setup. Most people do 2.5 turns out. From the factory the screw is blocked by a brass plug. The plug can be removed by drilling a hole in the plug, inserting a screw into the plug, Gripping the screw with a pliers or a similar tool, and pulling the plug out. Be cautious when drilling: once the brass plug is drilled through the mixture screw is right behind the plug, and can be damaged by the drill bit. This is done for both carburetors. The locations of the screws are shown below. (use a 5/32 drill bit)
 
Power increase: Very slight power increase if any, and the motor runs better with the richer needles.

These needles are the stockers (The other ones are in my bike).
Although, they look almost identical to the aftermarket needles

This is a picture of the front carb, the mixture screw is shown with the brass plug already drilled out

This is a picture of the rear carb, the mixture screw is shown with the brass plug already drilled out