The ZEX kit for 5.0’s is a dry shot system which uses a spray nozzle that’s tapped into the air intake hose for delivery. The instructions that came with the kit are a little bit confusing so I decided to create a simple install sheet making it much simpler and to clarify a few things I discovered while installing the kit in my Mustang.
First off, check to make sure that you have at least 4.2 volts at WOT, If you don’t, try and set your TPS so that you do without going over 1 volt on MAF cars at the KOEO and for Speed Density cars, your TPS setting should be right at 1 volt or a tiny bit over, but not under 1 volt as throttle response will decrease a lot. Decide where you want to mount the bottle and then take the long 15’ braided line and make sure the routing you choose will reach both ends safely. I installed mine directly over the rear pass side seat (when it’s lying flat) and had about 2 extra feet of line left over should I ever decide to mount the bottle in a different spot, such as all the way back near the hatch or in the same area but behind the driver. Once you have located the area to mount the bottle, use a black felt marker to mark where the bottle bracket holes are to be drilled and install the brackets.
Next is routing your main Nitrous line. Once that has been completed, locate a good mounting spot for the NMU (Nitrous Management Unit). CAUTION! The Nitrous feed line that taps into your air intake tube and connects to the NMU is only 2 feet, so remember that when mounting the NMU. Once you have found a suitable place to mount the NMU, use a center punch and hammer (If needed) to mark the spots where the 4 sheet metal screws will be used. Drill 4 small holes that are just a tiny bit smaller than the 4 screws and proceed in securing the NMU in place. The kit comes with a tap in case the intake tube is metal. If this is the case, drill a ¼” hole where you plan to mount the Nitrous nozzle, use the enclosed tap to create the threads. If you’re installing the kit on a MAF equipped car, make sure to install the Nitrous nozzle after the sensor but before the throttle body. If installing the Nitrous nozzle into a rubber hose, mark the spot then remove the rubber duct and drill a 7/16” hole and install the bulk head fitting. Make sure that the Nitrous nozzle is in the direction of air flow.
Once it’s installed, connect one end of the 2 foot piece of braided steel line along with the appropriate Nitrous jet and the other end connects to the NMU with the fitting labeled “Nozzle”. The kit is supplied with two 2 foot rubber hoses. IF you’re mounting the NMU under or next to the air filter box, the rubber hoses will be too short. You will need to run to your local auto parts store and purchase 1 3 ½’ hose (3/16”) and 1 4 ½’ hose (3/16”). Completely remove the factory fuel pressure regulator line which connects from your FPR to a steel vaccum line under the upper intake manifold. Take the 3 ½’ rubber hose and connect one end to your FPR and the other end to the NMU where it say’s “Regulator”, then take the 4 ½’ piece of rubber hose and connect one end to the steel vaccum line that your FPR hose was connected to under the upper intake and the other end to the NMU where it says “Intake” using the corresponding fuel jet and hose/barb fitting. (Hold on to your factory FPR hose in case you ever remove the system). Now the only fitting left is on the opposite side of the NMU which is where the main N20 line connects to.