Servo and Exup - call me a noob but wtf should I do???

Ok, I've done some mods (flapper, rear break light assembly, 12 tooth, KTM folding mirrors, and some others) but I will soon be adding a full FMF exhaust (Q4, header and EFI) but my question is;

What is all this talk about the servo and exup? What are they? Do they have to be removed or modded and why? Is it neccessary when changing exhausts? And most importantly how to do it all, step by step (with pictures maybe???)

Thank you so much!!!

The EXUP valve is a butterfly plate controlled by an electric servo motor.
It's built into the muffler, a few inches in front of the muffler "can".
It opens and closes according to the bike's electronics.
It supposedly gives more low end torque, but, in my opinon, these days it's more about reducing exhaust noise at certain throttle positions and RPM.

Removing it is no big deal because when you remove the stock muffler, the EXUP valve comes off with it since it's built into the stock muffler.

The servo motor that controls it is where the money comes in.
You can either leave the motor in place and plugged into the wiring and call it a day, or remove it and substitute where it once plugged in with something to fool the bike into thinking that it's still there.
This is usually called a servo sub or servo eliminator.
If you simply unplug it and ride, the bike runs fine but lights-up an orangy-red CEL (Check Engine Light).

Search for "servo eliminator" or "servo sub".