Im looking into buying some vance and hines short shots for my 09 dyna fat bob trying to get some info if I need to purchase programmer as well or not.

 

Not necessarily. If you plan on doing more, you may as well.

 

Just pipes=No
Just a/c =No
Pipes+a/c=Yes

 

It's old enough to have been modified already, perhaps replacement air filter? Opinions vary from: it's OK to make simple changes, through to: even a stock engine will benefit from a tuner. Personally I would like to be confident I'm getting the most out of my mods, also that the engine is running well. So that's a yes!

 

You dont have to with just pipes. But you are still running lean if you are on the original harley map. A tuner can only help.

 

Is it required? No. Would it be advised? Yes.

It will prevent long term wear from the lean condition set by the factory fuel maps.