So I just bought an 09 Nightster and came with V&H Sideshots and a Stage 1 that has been remapped. I however am looking at purchasing the Screamin Eagle Heavy Breather just to make it my own a little more but my question is since my bike has already been remapped with the stage 1 kit will it need to be remapped again with the heavy breather? Thanks in advance.

 

That combination should be fine with your current map. Perhaps you'll want to look at some aftermarket fuel managers such as XieD or FuelPak.

 

I know a little bit about doing that but not a ton. What would be the advantage of doing XieD or FuelPak? I would imagine I would get a little horse power and torque gain but other than that anything. If I didn't would I end up hurting my motor at all? Thanks for the patience with me not knowing too much.

 

XieD's are relatively simple and harmless. You'll want to watch your plugs to make sure you're not running too rich or lean (you'd probably want to do this even without a fuel manager).

I recommend against the FuelPak. It's considerably bulkier, and for your needs I think the XieD's would be more than sufficient. I have a FuelPak personally, and it's kind of complicated to get the thing to fit anywhere.

I still think you can run the heavy breather without re-mapping, but at the cost of a set of the plugs (around $50 used in these forums), it's likely worth it.