When you first look into one of K&N's popular airbox systems, you ask, "Why doesn't the factory just do this stuff up front?" Actually, there are a few reasons. The first reason that you don't see systems similar to this Gen-2 Fuel Injection Performance Kit (FIPK) is expense, as the factories will always find a way to cut the cost of what's included on a vehicle. If they didn't, that MSRP would be sky-high! Secondly, the tradeoff of noise for power that comes with an FIPK is one that they're not willing to bet each and every customer would accept. Plus, every vehicle presented for sale in America is subject to the EPA's drive-by noise standards and this kit might put that figure over the top. That's also the reason why you don't see a free-flowing exhaust kit on most cars and trucks (when it would be just as inexpensive to build it for power). Remember, not every consumer is like us!
K&N's FIPK systems are a relatively easy install that merits power through the use of a giant K&N filter and an improved box. Though some notice a slight loss of power at "tip-in," where the factory airbox has an edge at delivering air for low-end torque, a stomp on the gas once equipped with this aftermarket system will quickly tell you that this was a change for the better. For those who want a bit of improvement without the noise, they can replace the paper element with an aftermarket air cleaner (Holley, Rush by Barry Grant, and K&N all produce quality examples that flow more air than your car can utilize). However, hot rodders looking for serious power gains should consider a kit like the FIPK. Remember, the install you see here is very similar to that of the Ford and Dodge trucks, so this story should give you some insight on just how simple the process can be.
For this install, we chose one of Chevy's most desirable and increasingly popular trucks, a Silverado 2500 HD with the 6.0L Vortec V-8. With a bit more stroke than the smallish 4.8L and common 5.3L engines, this is the balance between towing capacity and fuel economy that has many people avoiding the big-block and getting the benefit of the biggest small-block that the General turns out. Let's see how it works!
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After disconnecting the battery cable and loosening the hose clamps on the throttle body the factory intake tube comes right off. Then, you can pull on the factory airbox (Man, there's a lot to this thing, it's giant.) and remove it from its rubber grommets. There's a mounting tray below where the airbox once lived, so you'll want to loosen the mounting bolts there, too, as it's where the new system is going to install. | 
The new box is actually a metal tray that acts as a heat shield (remember, the key to power is cold air) and is sealed to the hood by a piece of foam (which you shape around the tray and cut to fit). You must carefully remove the mass-air meter from your old airbox and install it on the FIPK and don't forget to read the directions closely to see how to sandwich it between the gasket and the heat shield. |
The heat shield, with the mass-air meter attached, simply bolts into the airbox's old home and there is lots of room to add that giant, re-useable filter. | 
Adding a silicon hose for attachment and installing the tube is a no brainer. Compared to stock, you have a system that looks racy and makes more power for under $300. Don't forget to put that smog-exempt decal under the hood, too, so that you don't get hassled if you're living in a state or municipality with emissions testing. |  |
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A run on K&N's Dynojet chassis dynamometer proved the FIPK's worth on this 6.0L Vortec-powered Silverado (a 2500HD with four-wheel drive and a taller, 33-inch tire). We had regrettably changed the stock paper element to a K&N replacement when it arrived off of the showroom floor, so we don't have a true baseline pull (sorry, testing fiends). | 
The improvement is still significant. In stock trim, the truck produced 238.8 hp at 5,200 rpm and 270.6 lb-ft at 4,150 rpm. With the Gen-2 FIPK under the hood, this Silverado produced 249 hp at 5,100 rpm (nearly 11 hp more at 100 rpm earlier) and 281.3 lb-ft at 4,100 rpm (that's also 11 lb-ft more torque). What's even more interesting is that it gained it gained more power higher up in the rev range, so our instincts about a bigger gain with more throttle makes sense. A recommended upgrade, we say. |
SEVEN BOLTS FOR SEVEN HORSES
A Simple and Effective Bolt-On Exhaust Upgrade for an S-10
By Scott Parkhurst
While the little S-10 we're focusing on in this story wouldn't make a great tow vehicle, it's a fine daily driver/parts runner. The anemic little 2.2L four-popper won't break any world records, but the fuel economy, cheaper insurance rates, and lower initial investment price all contributed to deciding it'd make a fine commuter vehicle. The benefits offset the "negligible" fuel economy delivered by a big-inch V-8 designed for serious duty. It's got such niceties as ABS and a driver-side airbag, and after it gets a mild lowering job and a decent wheel/tire upgrade, it should prove to be a capable way of getting around town.
If a few more ponies and better aural attitude are simply a couple hours and a few dollars away, why not see if we can add more pickup to the pickup? A basic catalyst-back exhaust system is a good call, and in researching this story, we found plenty of access to the components under the truck and a system from MagnaFlow that would bolt right up. We wanted to see how much rear-wheel horsepower (if any) a simple upgrade like this would add. We did find 7 hp, which may not seem like much to readers used to seeing much more. But, when you consider we started with less than 100 horses, that's almost a 10-percent gain with minimal effort and expense. We'll add a high-flow airbox/filter assembly later and hopefully pick up a couple more horses. These higher-flowing additions may add power we can feel in the pedal, but in freeing up the engines breathing capabilities, we're also making it easier for the little powerplant to pull us down the road. This means we should see increases in fuel economy, as well.
The entire exhaust system upgrade forced us to remove and replace a total of seven bolts: three at the back of the catalytic converter, and four securing the clamps at either end of the muffler. The stock hangers were re-utilized, and the system looks, works, and sounds much better. Easy? You bet--and there are plenty of upgrades just like this that allow you to tailor the look and sound of your system to meet your personal tastes. If you've got a factory system under your pickup now, it's worth the effort to investigate the many options out there for your particular ride. We did, and the simplicity was rewarded on several fronts. Check out the photos to see how easy it was to work with seven bolts and find seven horses!
Dropping the factory system was no sweat. There are the three bolts tying it to the catalytic converter, and the rest is secured with the factory rubber hangers. We hit the rubber hangers with penetrating oil before trying to remove anything--it truly helped! | 
Seen side-by-side, we can see where the MagnaFlow system (PN 15706) adds a bit of diameter (2.25-inch vs. 2-inch) and smoothes out the bends. The factory muffler is both quiet and restrictive, where the MagnaFlow part is a high-flow, straight-through design, and the pipes have gentler bends. It all adds up. All MagnaFlow catalyst-back exhaust systems are stainless steel, too. We'll never worry about corrosion. Careful design and top-quality manufacturing methods and materials make for exhaust systems that should out-last the vehicles they're installed under, and that kind of insurance helps justify the investment. |  |
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Back on the rollers, we found a nice power gain all the way throughout the rpm range. Check the chart for the numbers, but the tiny truck feels a bit more peppy and sounds like it wants to be a full-size some day. That might take a V-8 to accomplish, but for now, we're very satisfied with the direction our little shop truck is headed. Once it gets the proper stance, wheels, and tires, we'll call it finished. |  |
Wheels and Tires: A World of Difference
The world where hot rods and trucks cross is far different than it was, say, five years ago. Though the classic truck scene is growing as quickly as people can find likely candidates (It's easier to find an old Ford F1 than it is to get you hands on an un-cut Chevelle.), the sport truck scene has slowed down a bit. Actually, it's still huge, but it's more about useful trucks than the airbagged scrapers and sky-high monster trucks of a few years back. A huge part of getting a new truck working right (and styled correctly) is the wheel and tire selection.
As part of the Truck Tech segment, we bolted up a set on this Silverado to see just how big of a difference we could make with only the removal and replacement of lug nuts. From the before-and-after photos, you can see that the changes are huge. Lowering kits are still popular, but usually to get a 2-inch front and 4-inch rear drop rather than the 4- and 6-inch kits that still have some popularity. Hotchkis is doing a great job with the Silverado, utilizing a rear bar (many trucks omit it from the factory to save dough) that's balanced to the front, all-new rear leaf springs, and a result that'll smoke many cars on the street! Don't forget to match it up with a shock, too, as you can't expect the stock version to keep up with the revised spring rates. On this Silverado, we're still expecting to tow so we're leaving the "stink bug" look on the rear, but we'll switch out the bars as soon as we get a chance.
The tire companies have made a lot of changes in five years. Not only are the tires that they're building featuring more grip, better braking, less noise, and a better ride, but they're on the market with every size imaginable. We see the occasional 22- and 23-inch versions on the street, but the majority of the late-model truck and SUV owners and picking between 17- and 20-inch for a balance of the above qualities. In this exercise, we chose Yokohama's AVS S/T in a 285/55/18, a low-profile tire with the unidirectional tread (for both acceleration and braking) that you'd expect from a g-Machine tire on a '69 Camaro! The sidewall supports the reasonable handling loads that you'd throw at it, while not being so stiff as to providing an uncomfortable ride. With more inflation, you can tow all day, and with a little less the tire rides nicely and handles impressively. The Plus-2 move up from the 265/65/16s that came on the truck is unbelievable. The wheel companies haven't slouched either. Styles change every year, and you can there's a huge range of styles based on strength, weight, and manufacturing now on the market. Being hot rodders, we went with Weld's EVO series Velociti 6, fitted in 18x9 here. What makes this style of Weld wheel so special is that it's a one-piece forging. If you know anything about manufacturing, you can picture a gigantic press slamming down on a small ingot to press out one of these wheels into a shape of pure grain--simply amazing. Strength and light weight are a result, and the latter is really important, as the 18-inch and up sizes can get a little heavy. This 6061-alloy is very pure, so the six-layer chrome finish is impecable.
This two-wheel-drive 1500 truck (read "half ton") doesn't have the fender flares of a four-wheel-drive model or a Tahoe, so that 285/55/18 on an 18x9 (with a 20mm offset) sticks out just a hair, so little that no one notices. It's a universal fitment on this truck that provides a huge improvement without sacrifice. The wheel and tire may be heavier than the old 16s, but the lighter wheel and the sophisticated tire makes for a near-even swap in ride quality, the look is dramatic, and the truck is more fun to drive.
Before we go, we need to make the recommendation of using a Hypertech Power Programmer with any of these wheel and tire swaps. If you change the thermostat to Hypertech's 160-degreee model and commit to running 92-octane fuel, you can install their power map for great results. We didn't want to switch either (cheap, lazy bastards that we are), but we did tell the amazing little box, which installs a new map through the truck's diagnostic port, that the new tire we added was taller (it has a 30.5-inch setting, when this tire actually measures 30.4 inches in diameter), and that we now had V-rated tires, so it was safe to remove the 97-mph fuel cutoff and install a new limit at 128 mph. That should make the driving on the open road a little more interesting.
Cameron Evans