hey there.. Don't get discouraged by the lack of responses to your post. I myself was tempted to back out without replying, but I remember being in your position.
There are MANY threads out there regarding "necessary" mods. Off the top of my head, people will say
1. change tires and upgrade rear to 55 profile
2. Ivan's tune (2016 and older)
Personally, I've done none of the above. My order of operations was:
1. Add KQR bags/rails
2. Install RAM mount for phone
3. Install Sargent seat
4. Wire in voltmeter/usb charger and garage door opener
Main reason I haven't done any of the first three I mentioned is simple. My old bike was a 1990 ZX11. I loved it, it was fantastic and I thought I'd never upgrade, however I grew tired of messing with the carbs every season, along with other maintenance items due to age/wear at 30k miles. Insert my '16 N1K.
By comparison this bike is light, nimble, smooth, and fast. Not that my ZX11 didn't scream, but this one transfers much more torque to the ground, at least by my butt dyno's measurement. I am for sure going to do the Ivan's, but doubt I'll spend for full header/exhaust setup. May go with Urban Brawlers just to change the look.
Side note: My main riding would be considered commuting. I often have my KQR bags on and am heading to or from work. 2 young children at home, so rarely do I just take off for the afternoon for joy riding. As such, I'm nearly never in a full lean or carving through back to back twisties. Your experience may vary