Hey so this is my first post, but here are my thoughts:
I have a JB4 with gapped down
Denso plugs, BMS intakes, ADD Oil Catch Can,
Badge swap, and Eibach rear sway bar (set to soft), and am now considering an intercooler. I put these on the past month after driving my 2018 AWD GT stock for 28k miles.
They are all great upgrades, and a lot of fun, but if I had to pick just one of them to improve the ride and enjoyability of the platform, it is definitely the Rear Sway Bar.
With the stock bar, the back tends to float and understeer, especially on uneven turns. After the sway bar swap, the ride is so much more sure-footed and confident, without sacrificing virtually any comfort. You can have all the power in the world, but if you cant take turns and control the vehicle like you want (I even felt the float when casually driving from point a to point b), then what's the point?
The bar costs about $300, and I payed a shop with a lift 95 bucks to put it on.
Good luck and have fun my friend! Upgrading your ride is an addictively good time.