What kind of turbo does the 173hp C5 have fitted.

[Baldy-Old-Troll]

Hi, sorry if this is an obvious question but what kind of turbo is fitted to the 2008 173hp C5?
I know it's a twin turbo set up but is it variable vane or fixed as I understand twin turbo systems can use both. I'm having underboost issues and this stupid car can't even throw a warning light when it goes into limp home, the only indicator is loss of cruise, and eventually the loss of power is felt, not much use on the roads I drive where overtakes have to be decisive.

[Quackers]

I had this last month on my 173BHP C5, was driving a long and limp mode came on , lost power and complained about cruise control and speed limiter on the screen. My garage traced it to one of 2 turbo sensors, they could not be 100% sure which one it was so they did an educated guess and it was the manifold boost pressure sensor.

[Baldy-Old-Troll]

Thanks, I've already changed the Map sensor, and put an egr cleaner spray through it, car has been smoke tested, vacuum has been tested and waste gates appear to be moving freely, trying to find a local mechanic that can get to the bottom of it as the last two have let me down.