Yeah i did exaclty as you described above and the actuator held 10psi all day long, all the boost pipes are new Samco's, and the IC is a new Airtec, I think a pressure test of some sort might have to be the way to go before we start changing the turbo about, but saying that he was previously on a stock T3 and that had no problem holding boost so it does point to it being the turbo as nothing else has changed (we were told it was a good one, but who really knows).

Interesting that all exhaust housings crack, didnt realise this was the case, trouble with a .48 housing is your adding lag
In this particular instance it is a .48 housing anyway and he wants to drop back to a .36 to gain some response so if it is cracked we'll be sure to find one thats not cracked....... at least not to start with! lol