I did clear the codes, took her for a spin, same again, less jerky though, more like a smooth hissing/tornado!
Exact same codes came back, but no "17705 - Pressure drop between......." though, just the MAF one!
Will check boost pipes tonight when I am back from work "again" because it does sound like the turbo is producing loads of boost, its just all going to waste.
I will be back.