Why don't you measure it yourself?
If you don't have a digital multimeter, buy one. It's only a few dollars. If you haven't used one before, learn how to. The tool and the knowledge are useful in other applications as well.
I have an expensive multimeter used in the lab. But I also have a few of these ($2.99 a copy) laying around the house, in the garage, in my car, in my office just in case:
7 Function Multimeter
To measure the trigger voltage, set the multimeter to measure 1000V DC (or any value above 300V), let the flash charged up, apply the ground probe to the connector on the side of the flash's hot foot, the other probe to the center pin of the flash's hot foot and read the value on the multimeter.