If I install a set of Vance & Hines Straightshot slip-on mufflers on my stock 2015 FLS, will it require remapping?? Thank you for any help!

 

Some say the bike doesn't need a "tuning" just for mufflers, but you should invest in one.
The bike is produced very lean anyway. A good tune will correct that.
A lot of us bought the Power Vision from Fuel Moto.

 

Nope. Your not changing enough.
It's all about air flow and fuel mixture. Just the pipes won't change enough air flow,, it's still restricted by the Air Cleaner size.
If you change the Air Cleaner to a more free flowing model along with the pipes,, then,, you'll need to look at changing the fuel mix in some way.

 

Just going with the V&H Big Radius 2into2 needed a tune, and prior to tuning it had a whole lot of decel popping.

Changing Air and/or Gas flow will require a tune.

I have the TTS MasterTune and like it, but the popular choice these days is the Power Vision.