I’m close to pulling the trigger on this, but just like everything, I’m overthinking it.

I’m not planning on doing uca’s. From the majority that I’ve read, it sounds like it’s possible to get a good alignment without them. But, I’ve also read of premature tire wear and poor driveability.

Any first hand experiences?

I put the frt struts on @ 0.85 height to level mine in Nov. 2020 have 21k on it W/Cooper Discoverer S/T MAXX 275/70/17 never had alignment & no unusual tire wear. I do need to get aligned at it is pulling slightly to the right now.

Aligns just fine with factory upper control arms! I ran the stage-1 kit on my 2019 SR5 4WD for years and never had any issues (i now run the Stage-2 kit). Give me a call if you want some more info on the kit, Ill be more than happy to answer any questions 951-256-8422 (office phone). I actually work at Eibach, so I can give you any technical info you need.

Factory UCA are good to 2in of lift easily.

That said if you need a stupid amount of caster then maybe not

It aligns fine but i have noticed that I come out of alignment more often than I would think reasonable. I'm pulling to the right and it's been less than 10 months. I don't do more than fire roads to campgrounds.

Personally, I think the suspension rides rough being that it's digressive - def wouldn't recommend it with KDSS. I suspect Eibach does not customize the compression for 4Runners.

I don't think Eibach did much testing of the suspension on a 4runner when they first released it - mine were purchased within a year of release. They had no idea how much a bumper/winch combo adding 125lbs to the front would affect the set up (ride height, pre-compression, how it would ride, etc).
Maybe they've gotten better but I would look elsewhere.

Oh 1 word of caution.
Make sure the snap ring is FULLY seated If you're using the existing coils. I know from experience when I set it down off the lift Pax side made loud bang. Sure enough The snap ring popped out. Luckily they provided an extra set so I just went ahead & put new snap ring in & tapped W/hammer to fully seat it. No issues since Nov.20 & 21k on them.

Thanks for the information everyone. I’m pulling the trigger on this, just waiting to see if there is any 4th of July sales.