If you're driving a majorly tweaked car... it will turn better in one direction than the other...
I think that is the point, there may be a few PRO 4s with major tweak but I would of thought that with most it was minor because I dont think Hpi would have released them if this was a major problem. And up to a point a car turning one way better can be compensated for with other settings and a some people are looking for that perfect car to improve they lap times.