Hiya mate,
There is nothing wrong with the 24v kits, quite the opposite - they are a bit too good
If you leave them at standard settings they give you a bit more top speed, better hill assist and slightly better acceleration. But not enough extra performance to really justify the cost.
It's when you start altering the settings to get more oomph that it all goes pear shaped - the gearboxes simply cannot cope
Shame, because while it lasts the C5 on max power is a real blast
We've withdrawn the 24v kit from C5alive for a winter revamp. We're going to improve it along the same lines as the power wiring kit and attempt to find a solution to the gearbox problem.
The kit you mention was from the previous version of C5alive, you might want to check and see if it comes complete with the twist grip throttle. Some kits did not include this.