In California, like most other...
In California, like most other states, we have to fear the smog police. K&N has taken care of our worries by getting the FIPK an exemption number from the California Air Resource Board. This sticker certifies that the system is legal to install and is include in the kit.
Reprogram
Every car built today is computer-controlled. That means that the key to unleashing any additional power ultimately lies within the computer. Unfortunately, you can't just plug a laptop into your car and hit the "more power" key to download performance. You can, however, plug in a unit like Hypertech's Power Programmer and get better performance in a matter of minutes. Besides reprogramming the fuel and spark curve there are other items that the Power Programmer can tweak. With it you can change your vehicle's top end speed limiter, alter the automatic transmission's shift points and shift firmness, recalibrate the speedo for new gears or tires, and raise or lower engine-operating temperature for max power. You have the option of programming in any number of these features individually or all together depending on what your vehicle and/or heart desires. And all of the new programming can be removed and your factory-stock settings reinstalled in just minutes because the Power Programmer saves the stock information in its own memory, which cannot be erased or overwritten, ever.
Real World Power
Before you read the power chart from our dyno test remember that a chassis dyno measures power at the rear wheels, which can be anywhere from 15 to 25 percent less than measured at the flywheel. That's simply because it takes power to turn the transmission, driveshaft, and differential and that power cannot be recovered. To clarify this point, if you calculated the observed power figures from a chassis dyno session, factoring in a 15 to 20 percent drivetrain loss, the improvements would more closely match those claimed by manufacturers in their advertisements.
Power Numbers
First, we baselined the truck to get some stock power figures for comparison. Surprisingly, the 45,000-mile '97 Chevy 4x4 we tested produced unexpectedly high rear-wheel power figures. GM rates the truck's 5.7L Vortec V-8 at 245 flywheel hp. K&N's chassis dyno revealed that this truck was putting 212.3 of those hp on the ground. Some simple calculations tell us that if the engine was indeed making 245hp at the crank, then we're only losing 13.3 percent through the drivetrain. However, peak power numbers hardly tell the whole story when you're testing street components and we prefer to use average power figures to determine if a bolt-on was really worth it. Stock, the truck averaged 180.2hp, so this figure will become our baseline. It should be mentioned that all components were tested in both Second and Third gear, but the best power was produced in Third, so that's what we'll list.
Here's K&N's new stainless...
Here's K&N's new stainless exhaust laid out next to our old factory stuff. The smooth mandrel bends and better flowing stainless steel muffler makes the system a worth-while investment. And it sounds ultra cool!
With a baseline established, in went K&N's FIPK system then we drove the truck around town and on the highway for approximately 100 miles to let the factory computer adapt to its better breathing components. After strapping it back on the dyno we were immediately rewarded with an average 8.3hp increase bumping the average peak output to 188.5. Even more impressive was the 10 to 15hp gains observed between 65 and 75 mph, where many of us spend most of our time. So not only did the FIPK bring the entire power curve up, it fattened up the middle where it will do the most good.
Next we installed K&N's new stainless steel exhaust system which consists of a flow-through design muffler with 3-inch mandrel-bent stainless tubing leading in and out and finished with a chromed-stainless exhaust tip. Since it does not change the location of the O2 sensors or the catalytic converters, K&N says its exhaust is legal in all 50 states. After another 100-mile test drive and a few pulls on the dyno the exhaust did not net a huge power improvement, but in the time we've spent behind the wheel following the test we've been rewarded with improved fuel economy and much more attractive acoustics. With the new exhaust in place, there was as much as 10 additional hp gained at the rear wheels on the dyno.