I believe there were a couple of members mentioning in the past that they were told they would need to purchase a CHIP to get the additional speed from their stock controller when actually it's just a code that's entered into it by a factory Handheld Programmer along with the purchased Private Code 4 from Club Car. I've attached a link to a PDF file of the instructions from Club Car if anyone is interested in viewing it or learning what it's all about in the future.
http://www.tk411.com/pdf/speedmode4.pdf