That's strange. Luckily the lock isn't overly important, you just have to find the range that works for you, based on time and experience. If it feels like it takes too much effort for a smaller input, the value needs to go down, and vice versa.
And I haven't really given (extensive) tuning a shot. I'm far better at tuning/tweaking in GT, though I'm familiar with how everything works in Shift. I can happily help you out if needed, but I would have to do a bunch of testing to get you a good tune, as I don't just have tunes at the ready.