Too much caster??

I wouldn't go anymore than 5* and that would be for a manual steering car. It might get to where it feels kinda "rocky" when you make lane changes with that much, so you may need to back off a little. It sorta will feel like the car is trying to "fall over" in the front. You'll know if you get too much. Of course with aftermarket control arms, a lot of those rules are thrown out the window because the angles are different and some of that is engineered out so that they can get a high amount of caster. remember though, it all depends on what you wanna do with the car. Want it to handle good? then a real high amount of caster isn't good. I would set it at 3.5* and see how it drives.