hi i have a serena 2.0 td limited imported from japan i have a few probs with it but i think the are linked first it is quite heavy a fuel second it is a bit of a slug and third which is i think the cause is that when you are driving along nice and steady it ok but when you put your foot down it dumps its turbo presure and hisses untill you take your foot off the more weight in the car the more it does it help please

One of the intercooler hoses is leaking and allowing the turbo to loose boost pressure. Get new hoses or get an exhaust shop to make up some stainless steel hoses