I'd say he say he is spot on TBH, maybe a slight exageration.
He does say he had 170mph, which is totally achievable. The problem is nobody really knows the top speed of these cars, mine is apparently good for 180mph, but you need to find a long enough stretch of road. I could easily wind it up to 150-160 I'd say.
I think the guy posts on the HSV site, nice looking car.