On first starting when engine is cold there is a strange whining or high pitched humming noise which increases as you rev engine, but goes off after a 5 mins or so as engine warms up. Not sure if this is possibly a loose belt or something more serious? I did also notice excess smoke from exhaust but again that may be due to being cold. Also the turbo boost gauge seemed to fluctuate whilst revving at a standstill but seems fine whilst driving?