Not sure if I'm reading that right or not but the horn shouldn't be straight up and down for the steering to be centered.
No matter what steering setup you are using, the rod or link should have a 90° angle to be centered and with the horn straight up and down (like most cars want)... it's not at a 90° angle.
Get it as close as you can to 90° and use sub trim to get it to a 90.
Hope that makes sense.