How new is the air filter? Any dirt in that will make things worse as is a further restriction.
When turbo spools up, it sucks air in. That pipe has an air filter on the end so is restricted. This creates a vaccuum and the pipe gets sucked in on itself, cutting off air and killing engine.
Try squeezing the pipe when it's all hot, if it's really soft then chances are it is at least partially collapsing.
Cheers mate makes sense. Didnt know there was a filter on the end of the pipe... unless your meaning the airbox? If not can you take the filter off to see if its full of crap?