OK.. I spent the day removing every type of hose on the car, checking them and cleaning them, i think iv sorted the hissing noise, coming from the black tube in the middle behind the inlet manifold, i think its the auxilery?? and found a small gash in the end of the boost hose that goes from the bottom of the turbo to the intercooler, i cut the pipe down a bit and put everything back together, it started but still kept cutting out, and im 100% that the pipers are all good, iv checked them thoroughly. any suggestions? thanks