If there's a leak, shouldn't the pressure sensor trigger an alarm?
No, he doesn't! And secondly, the described 'gurgling' sound is extremely unlikely to come from a constipated cat.
And @durts: I wouldn't drive that smoky car around for too long, I drove mine until the VTG was jammed!
Unfortunately, it's the turbo... the shaft is very difficult to turn... so there's no need to look anywhere else. Is it possible to repair it? Hopefully!
And by the way, the car has been completely disassembled and packed up for a week now.