The intake system for the 4.6 and 5.0 V8s is the same for all models, including Equus up until the new chassis in 2015. The new chassis features two separate air filter boxes, a recognition by Hyundai that the original system is very restrictive. The original system draws ambient air from the front of the radiator up and then over and down to the air box, which contains the filter element. There are at least five 90 degree turns in the intake tract. In addition the air filter element itself is comparatively small. The benefit of all this restriction is almost no intake noise. There is the famous air box flap inside the air box, which can be easily removed for a somewhat more direct air path. This is a simple no-cost mod.
The next mod in a performance evolution is to change out the entire air box for a stand-alone cone air filter. From time to time vendors promote so-called “cold air intake systems”, usually costing several hundred dollars. These systems consist simply of a cone air filter and a provided shiny metal intake tube from the air filter to the motor. They are not true “cold air intake systems”. A cold air intake system typically has a “dam” built around the new cone air filter, which dam not only prevents hot engine air from the intake, but also admits only outside ambient air into the system. To date, no one has offered for sale such a cold air “dam”.
The shiny metal
aftermarket intake tube between air filter and motor is mostly cosmetic as the original OEM intake tube is not at all restrictive. In addition, the original OEM intake tube has a secondary air filter on the 5.0, which offers some performance gain. So, I retained the OEM intake tube. It costs nothing to do this.
Size really matters with the air filter. I wanted the largest cone filter I could find which was: K&N RF-1040 Universal Clamp-On Air Filter: Oval Straight; 4 in (102 mm) Flange ID; 7.5 in (191 mm) Height; 9 in x 5.75 in (229 mm x 146 mm) Base; 7 in x 4.5 in (178 mm x 114 mm) Top. K&N was an easy choice for me. K&N has been manufactured for decades now. It is used as an OEM filter in high performance options.
There are many competitors, some of which are cheap imitations. The K&N RF-1040 costs about $60 at Amazon.
You need a 4” o.d. metal connecting tube between the K&N and the OEM inlet (from the OEM air box). Tubing can be found everywhere. Spectre Performance #9719 is an example with a 6” length. This 4” tubing fits the K&N perfectly, but is a bit too large for the OEM intake. I used a tin snips and cut a series of 1.5” cuts into the OEM intake. It then accepts the 4” tubing. I wrapped the connection with black Gorilla tape and then a hose clamp. The mod is virtually invisible.
There is a loud intake noise now on WOT (wide open throttle), but at cruise/light throttle it is just as quiet as before. My “seat-of-pants dyno” claims a material power increase.