I just bought myself a a 2016 Street Glide with 6000 km's on the clock. Its a beaut, but it still has the standard mufflers. 

Ummm its touch and go with this. Std they are tuned lean (more air less fuel) to pass exhaust emissions tests. Now if you allow more gas out you really need more fuel to go in to compensate. A short ride on a warm day underload will tell you if its running lean as you will hear her ping, this is NOT a good thing for the motor at all. If you have a tuner jam in a new map now

PB is right.  I remember when I got my FP3, it had a map for stock pipes and air cleaner.  At that stage my bike was all stock, but just loading that map made it run better and cooler.

Fitted the new V&H twin slash round mufflers. Bike goes better, but it's getting too hot. It was a warm day but the increase in heat was noticeable. It wasn't pinging.

I have a unmarked set of Monster Ovals if you are interested? Cheap at $500 for the pair.

Bought a Fuelpak FP3 and installed a new tune. All is good now, bike is so much smoother.