I have just completed week 9 with the Powerbreathe.
This week I have moved up to level 5.5 and still doing my 10 breaths at half load, 30 at full load and finishing with 10 at half load.
In December I generally start to feel very tight in my chest when under exercise stress and this does affect my cycling as I struggle to get enough breath in.
I hope I am not tempting fate here, for the first time I can remember this year my breathing is significantly easier and this makes exercise much more productive.
If this continues I will consider using the Powerbreathe has been a success for me.