According to Parker's it's 177 bhp. Torque is 230 Nm/170 lbft. 137mph, and 9.2 secs 0-60. Parker's review mentions "when overboost is used, this increases pulling power to 266 Nm".
Big 70 litre petrol tank, 15.4 gallons. The Vector SE 1.6T was the entry model.
If everything works, and the receipts show the ABS and Stability electronics MOT fails stated in 2014 have been sorted, I can think of far worse ways of spending £5k on a big, fast, comfortable and economical saloon that is out of the ordinary.
Yes, I know, we all hate GM for what they did to Saab, but we are where we are. That said, it's likely that the engine is tuneable by any Vauxhall specialist, but personally I wouldn't do it to a ten year old engine with over 100k on it. That performance is as good as most big cars these days with small engines - VW Arteon, Skoda Superb, etc.