Wikipedia has said that for years but the park still say 2.5. Wikipedia isn't the most reliable source out there so I will go with the park and say it is still 2.5. After all, if it was any faster, they would promote it.
It did feel very fast at the weekend, though, it probably has new wheels and also may be slightly due to the fact it isn't high up over wasteland now, with it turning sharply just above people in the Thirteen queue, the entrance to Thirteen and next to the building.
It did feel much faster than before so it is probably new wheels, the launch speed is unchanged because the ride was designed to work at 62mph, and will not work properly any slower or faster.