I saw a Zebra recently:
The dealer said it goes 35. He was also throwing a spare battery in there to make it go even faster. it uses a 72V Alltrax controller.
Since it's a three-wheeler, technically it's a motorcycle. Therefore it is excempt from NEV laws.
Typically, the 25 MPH thing is because of regulations. You can make electric vehicles that go any speed you want, but high voltage tends to cost $$$.
I should get out to the Zenn dealer sometime. There is one about 45 minutes away. I will report on it after I actually get out there.