Can anyone tell me what the story is on a stage I install? What's that do for my 88B?

 

Take a look here https://www.hdforums.com/m_153730/tm.htm It lets your engine breathe easier.

Check out the rest of the forum while you are there too.

 

the stg 1 kit is a new better breathing air filter and a restrictor type plate behind the filter. thus more air. you will also need to re-jet or get a re-map (HD download) with my bike i gained about 10 hp with the stg 1 kit, pipes and HD race tuner.