13. Whether you use a handheld or a throttle-linkage-activated nitrous switch, you'll need to mount the special relay in a clutter-free area away from hot engine parts. We fastened our relay on the firewall just rearward of the master cylinder. Hook up the various power, ground and solenoid activation wires to the relay as the instructions show. All wiring is straightforward and easy--no degree in electrical engineering is needed.