dont waste your money on a speed code change.
First check your batteries as suggested--08 batteries on an old fleet cart and in a Precedent may be very weak. One bad cell and you need all new batteries. this will cause slow speeds and dramatically reduced run times.
Next once you ares sure you have good batteries...call a company named "Plum Quick", google it. Also there is a company called EMP, google thyem as well, but I have had great luck with plumquick.Their motors do away with the whole speed code issue and will get you in the area of 23 - 24 mph. it costs about $250 if you buy it. If you dont want to install it, call or e-mail me and I will install it for you in about 15 minutes...its that easy.
Also as posted earlier. Tire pressure and brake adjustments are crusial. low tires will slow a cart as much as 5 mph. dragging brakes will slow a cart even more. My guess here from a bit of experience...I see 4 new batteries and a Plum Quick motor in your future---total cost about $850-$900. Then you are good for a few years.
for more info than you could ever want--go to
www.buggiesgonewild.com