Likely cure? Turbo related question...

[Will]

I seem to have lost boost or increased power at the moment.

Now when I rev it up I can see the wastegate actuator engaging so it is boosting but it's not boosting hard at all, the air intake to the turbo is ok, the manifold is ok, and it drives fine, just not boosting it seems hard enough or properly. The blow off valve is hardly recirculating excess boost pressure so there's something amiss...

Could it be the intercooler pipes? That's the only thing I've got left I can think of - I haven't really checked those...