I have 12 dyna switchback with a VH slip on and if I change the a/c do I have to retune my bike and buy a VH fuel pak

 

Yes you need to tune. But it doesn't have to be the Fuel Pack.

 

No you don't. All the Harleys since 2007 when the Delphi fuel injection system was introduced can cope with stage-1 hardware without a retune.

The air fuel ratios won't be the very best for power but they will be the same as stock, which the engine is designed to run with. You will get most of the performance benefits of a tuned stage-1 but it will run hotter than a bike done 'properly'.

Most of the advice you will get contrary to this is based on pre-2007 (pre-O2 sensor) experience when the bikes couldn't cope with new pipes and air cleaner and would run lean enough to damage the engine.

 

Do yourself a favor man. Get your bike uh - "Done Properly".

 

Believe me, it is.

The question though was "do I have to retune". To which the answer is no.

 

Yes, you need a tune.

 

No you don't need a tune. Its just a good idea.

 

Id have to disagree, when I added pipes and ac to my 2010 it seemed to run fine until I accelerated in the upper range rpm's (ie: 70 in 5th gear) then I could tell something was going seriously wrong. Do your bike a favor and get a tune

 

There has been this discussion several times here. It comes down to those relying on seat-of-their-pants or out-of-date wisdom as opposed to those who have tested it, like American Iron mag (and me). I can't be arsed to go over it all again.

Do what makes you happy.

 

if your not running the **** out of it you will probably be fine