I added 12 mm spacers to the front of my G37 journey coupe. I've had experience with spacers and increased offset wheels, and I've had increased groove following and steering effort from them. But I've never had it make the car more responsive to steering input. It was already pretty sharp, but now it's almost twitchy at highway speeds; unacceptably so. I pulled the spacers to check, and that's definitely it.

Anybody got any experience on this?

 

I had 20mm spacers on my sedan for a while and I felt the groove following pretty badly. I didn't really noticed increase steering response - I felt that there was less response as the car wanted to follow its own path. I attributed mine to the face that my front wheels was on a wider track than my rear wheels which through off the balance of over and under-steer. i could be wrong though.

 

Is it possible the addition of spacers change the toe on your alignment? When toe is off, it causes severe tramlining.

 

That's funny you mention that, Chili - I got my car aligned after I installed the spacers and my toe was in spec. Since I've removed the spacers I don't have that problem anymore.