I use +3 for my DS4. Some time ago I discovered those thumb grips, and they really help me turning much smoother, with the right DS4 sensitivity setting. I bought two type of it to experiment with, and ended on gluing together two pieces that gave me the right height that worked for me. I ani't sure if I will be faster with a good wheel. For sure I will be much smoother, but it ain't guaranteed I will be faster.
So for now I'm fine with the DS4 steering, but the throttle traveling (R2) on the DS4 is simply too short to be smooth and linear. I wish there was a controller, with lets say 50% more traveling distance compared to the standard DS4 R2 button, for more smoothness on the acceleration.