I'm new here and I'm starting to do things to my 09 FLHRC. I put on Rinehart 4" slip ons a while back. Now I want to add a Screamin' Eagle high flow intake to the mix. I did not tune with the slip ons cause HD said not to worry about that with "just slip ons". So if I add the air intake, should I tune?

 

Yes, introducing extra air into the engine will require more fuel to avoid a lean mixture.

 

Absolutely, the engines are very lean as is delivered and to get best results you should have already tuned it, swapping the a/c out will have an effect as well, get it tuned and reap the benefits of the money you have already spent.