The Install
1. Stillen's technicians started by removing the mass airflow sensor from the factory intake with a No. 2 Phillips screwdriver. Then, the 10mm bolt on the back right side of the airbox was removed, and the worm-drive hose clamp securing the intake tube to the airbox was loosened. Finally, the airbox was removed with a steady upward force to release it from the retaining bolt. | 
2. Here is a side-by-side comparison of the stock unit and Stillen's setup. Right away, you can see how the new unit will be more efficient thanks to the straight-through design and, of course, the high-performance filter. |
3. With the airbox out of the truck, the techs removed the retaining bolt that holds the airbox down on the bottom. The rubber grommet on the bottom of our stock airbox and was placed into our new box. The MAS is located on the bottom of the intake tube, so it was installed before putting the intake into the truck. |  |
4. Staring with the inlet side of the intake, the techs inserted it into the opening of the fender that gave them room to connect the outlet side of the intake to the coupler hose and tighten it down. Then, the 10mm bolt was reinstalled to finish securing the airbox to the truck. | 
5. Here's our Stillen Hi-Flow intake system for Nissan '05-'07 4.6L V-6s installed. The upgrade looks good under the hood of our Frontier, and it provided 11.2 additional horsepower at 5,700 rpm. Not bad for a performance product that installs in less than an hour. |
The Final Word
For several days following the install, we had plenty of seat time in the Frontier to gauge the effects of the new intake, and we can honestly say that there is a very noticeable difference. When the throttle is punched, especially while cruising the freeway, the added power can easily be felt, especially in the truck's sweet spot. The sound of additional air being sucked into the intake is mellow enough not to be annoying on long drives. During dyno testing of Stillen's Hi-Flow intake kit, we measured a gain of 11.2hp (see accompanying chart), which is substantial for any stand-alone intake system.