Two questions. I have a 2012 jk on 3" lift with 35s. Would a bilstein steering stabilizer help with handling or just make matters worse.

I also am building my brother in law a RK 2.5 Max travel while he's deployed. Already did track bar, control arms and the kit itself. Would it be worth it to throw a stabilizer on there or leave it stock?

 

Unless the factory stabilizer is damaged or leaking, you really won't see a benefit with going to an aftermarket one.

 

X2, I've crush/replaced mine 2 different times on rocks. If I remember I'll take the darn thing of next time I go wheeling.
Freeways, it's nice to have and I have been buying the cheepies. Works fine

 

If you wheel your Jeep, a relo kit to get it above the tie rod is a good idea.

 

If it set up right you really don't need one at all. If it has handling problems now it will just mask them. Fix the problem first then you could throw one on it.
I have been running without one with 37's. Mine is a daily driver, just did a 500 mile road trip.
Couldn't tell a difference without it on there.
I feel the bumps a bit more Offroad but I'm eventually doing hydro assist.

 

X2 on relocating. Inexpensive way to avoid trail damage.

 

X3 on relocation. Move the stock stabilizer up and out of the way.

 

I've relocated mine and put on an OME. No difference that I can tell from stock. I've heard the Bilstein can cause your jeep to pull to the left. Love their shocks though!

 

Relocate for trail durability, replace for bling.

 

Best advice yet!