The Garage
No truck has been more influential for the automotive aftermarket than the Chevrolet Silverado. Throughout its history, the Silverado has sported a distinctively pure performance aesthetic. Void of excessive trim and molding and following designs true to its heritage, the Silverado has always had a minimalist style even though it's marketed as Chevy's premier truck.
For '08, the Silverado's 4.8L Vortec cranks out an honest 295 hp and 305 lb-ft of torque and still maintains 15 mpg. Adding a few extra ponies is a simple task too, when bolt-on modifications like an air intake will improve the quality of air the motor breathes.
Based in Phoenix, Arizona, the crew at True Flow dyno'd an '08 4.8L Silverado to get a baseline horsepower and torque number. They then developed an air-intake system based on their XDi system to maximize air-intake performance.
Installation of the system is straightforward. It is a simple replacement of the original equipment using the factory mounting location and retaining any and all emission and engine control devices. We could get into a step-by-step installation guide here, but even the most mechanically challenged will be able to tackle this project with basic tools.
What's In The Box?
The True Flow XDi line of air-intake systems comes with high-end components like four-ply silicone couplers, powdercoated aluminum tubing and canister, stainless steel hardware, and True Flow's proprietary foam air filter. Foam has been used for years in off-road applications such as motorcycles and off-road race vehicles. True Flow developed an air filter using fully reticulated foam cells and specially formulated oil to create a nearly impossible journey for dirt particles to enter your engine. More dirt in your engine means lower performance, lower gas mileage, and increased engine wear.
 |  |  1.As you can see here, the...  1.As you can see here, the factory unit leaves little to be desired. It is made of black plastic and is bulky and just not very cool in general. Stock units have a number of hang-ups in that they almost always use a paper panel filter and sound-reducing chambers, both of which hinder performance. Chevy did go so far as to incorporate a plastic intake manifold to reduce air-intake temperatures. Now, a quality intake will finish where the company left off. |
 2.True Flow's XDi retains...  2.True Flow's XDi retains the factory mass air sensor without throwing codes or any other headaches. Installation is simple because this is a direct replacement for the factory parts. |  3.The XDi says "look at me"...  3.The XDi says "look at me" when the hood is opened, while the factory unit falls on its face, buried in a compartment of black plastic. Silver tubing fitted with stainless clamps and red couplers looks trick. The big air-intake can looks like something right off a Trophy Truck. | |
The Final Word
The True Flow XDi intake setup looks pretty sweet and installs easily. Once installed, the truck had an aggressive sound when the throttle was opened up. Back on the dyno, a notable improvement in bottom-end power was recorded. At 2,800 rpm, torque rose from 138 to 168 and horsepower jumped from 106 to 115, which are noticeable gains when measured at the wheels. At around 4,000 rpm, the effects of the intake leveled off and matched factory power up to 5,750 rpm, where the test was shut down. Those bottom-end results, however, will do some good when towing, climbing, or during light-to-light acceleration. If you have a Silverado that needs a little more pep in its step, you should consider True Flow's XDi Intake.