Thanks for the replies so far. I thought the car seemed less agile than expected from the word go, but I didn't want to hold the accelerater flat to check. Anyways, I get no hiss on lift-off, no whistle on full gas, no nothing. The big giveaway is the crap power above 2500 in 4th, 5th, or 6th - so something is definitely wrong. I had a 2litre 16v astra a number of years ago, and it feels just like that in terms of power. i.e. non-turbo. Stealers said 'these things happen with modern cars'. WTF ?!?? After shelling out that kind of money I expect the car to have been checked - PDI anyone ??
Oh well, she goes in on Monday to get 'looked at' by stealers. I will report back after that. After all those months of waiting, the whole thing feels like a bit of a let-down now.