Mine will never come back to center..... ever. You can track in a circle all day long by bumping the wheel. It's getting much worse as the weather is cooling off too. I now have to physically steer back toward center, and get the right amount past it to get Beast to track straight, both directions. It's easy to induce PIO on a bumpy road. This is with anywhere from 6-7 degrees of caster (PR 44 unlimited housing, 10 degree split between caster and pinion). I don't think I can run 7 long term, I start picking up driveshaft vibrations at 70mph with 7/3. 6 should be MORE than ample. Keep in mind this is all low speed when steering efforts are higher. At highway speeds, it's much more predictable, and the road force drives Beast back to center better, not perfect, but better.
I have a suspicion it's actually the tie rod, but I'm willing to try all of it. I went out and watched some parking steering on a stock tie rod JK (granted, not lifted, stock knuckles, stock shafts), and the tie rod moves very differently for the last half a throw of wheel than it does with my Synergy. The Synergy also forces some creative mounting with any of my stabilizer setups, because it walks in and out toward the front and rear of the vehicle more than stock at extreme steering angles.
I ran this stuff just fine for ~10K miles. I wheel it hard (for the Midwest), and had an incident with a locker. I did find a post I made before the locker incident where I was complaining about sticky steering (first weekend after PR44 install) on the way to North Carolina (bought half doors on Craigs list). I installed all of the Synergy front end at that time when doing the axle swap. I have a strange suspicion that it's a perfect storm. Maybe you have to be running REIDS, RCV's, and the Synergy setup to notice this. I ordered stock stuff last night, when I install it I'll be sure to let you guys know the results.