Personaly my experience, I would not go lighter compression strenght then this. But thats my experience. I have tried all 4 springs i showed you guys in earlier post, and all of the three other ones made my camino downshift in the wrong powerband. I tried then to compensate with less weights, but then my bike had way to much rpm before it started to variate, and it made my bike slower from start.
All this is my experience. And it all depends on where you got the best powerband. Different exhausts would probably give powerband in different rpms. So you have to fine tune it with weights.
My experience is also that with more strength in the rear pulley, easier it is to fine tune it. But you need allot of weights to make it happen. And you also need heavier weights. You can compare this with tuned scooters, they also run heavier weights and stronger springs.
Sorry for my bad english :)