Hi guys, posted this on RSOC but thought I would put up here to see if anyone can help?

My saph, 2wd standard has been running spot on for the year I have owned it however after being laid up since November I have just taxed her again and have carried out the usual checks, oil, plugs etc.

Anyway when I am driving at low speed it is perfect, however if I floor the accelerator suddenly it begins to build boost and then jerks and cuts the turbo (violently), however if I gradually put my foot down the boost builds and the turbo spools no problem?

Just wondered if anyone had any ideas as was thinking it could be a split hose but which one would cause this?

cheers