Dwffy,
I did a
"contactor turbo-boost bypass" some time back in my Electro-Metro.
It was just a fun, wierd experiment. At that time, the car was setup for 72V, and I only had a 72V controller.
By using a dual-action contactor, I could disconnect the 72V controller, and directly connect in two more batteries - for 96V and more top speed.
It was fun and a little scary.
In that case, it allowed me to test out a higher top speed, and was a cool little experiment.
It's so much easier/simpler/better to just go with a higher voltage controller. Unfortuntely, they get expensive really fast. Building one yourself like the Cougar/Open ReVolt is a great way to go and keeps costs down, while maximizing performance.