The M50 intake is legendary for its air flow capabilities, which let engines rev freely past their factory manifold choke points - extending the powerband. For this reason, race teams have been custom retrofitting these manifolds for years, but we just made it easier!
Using our kit, including the throttle body adapter, ICV plugs, and port matching templates, lets go through some details on installation.
To install the M50 manifold you need to plug the ICV ports on the M54 head. To do so is easy, and can be done on the engine.
Plugging Head Ports
Firmly thread the plugs into the head ports using an allen socket on a ratchet. Thread them so they sit just below the level of the head. Then, remove the plug, apply some thread sealant, and then reinstall the plugs. This step is now done! The plugs can be removed and a M54 manifold reinstalled if ever needed. The manifold gaskets do not touch the plugs.
Now, the decision to port match is a personal one. The gains made are not huge, but port matching is worth it if you are going for every horsepower. Our included template makes port matching easy with a dremel. This can be done on the car, just make sure the valves are closed on the port you are working in, and that you use a vacuum and air compressor to clean out the port after machining.
Next you either adapt the M54 fuel rail. This is easy, just cut off the stock mounts and make small arms with some aluminum stock and a drill. Or, you can use the Rally Road billet fuel rail, like we do. If using EV14 injectors, use the Rally Road injector spacers as well.
ICV (Idle Control Valve)
If your engine is NA, you can use the factory M50 ICV lines to use your current ICV unit, it is the same as used on the M50. If you are boosted, we recommend the Reboot engineering ICV plug and Maximum PSI M50 intake hose kit to protect against boost leaks.
However, to retain the ICV, on a non-boosted build, just use a E36 M3 intake boot and icv hoses. Part numbers below.
Intake Air Temp Sensor
The M50 intake uses a threaded port for the intake air temp sensor. Luckily the stock unit found in your m54 can fit if you run it through a die to thread it. Just thread the outside sensor body and throw some sealant on it and you are good to go. Or, hit the easy button and grab a threaded one here : http://www.bimmerworld.com/Modified-Air-Temperature-Sensor-for-M50-Plenum-Conversion_2.html
Now, the intake has two extra ports. One small one in the front, which needs to go to your fuel pressure regulator- found on your fuel filter on most E46 models. The larger port, nect to the throttle bost will attach to your factory brake booster hose.