If you could pick up at least 11 hp in an afternoon, with about the same effort as it takes to disassemble and re-assemble the factory airbox, would you do it? Sure you would, especially if it didn't cost a week's wages and was smog legal. Granatelli Motorsports has engineered this kit for '99-01 5.3L and 4.8L Vortec-engined Silverados, Sierras, Yukons, Yukon XLs, Tahoes, and Suburbans. The big change is the use of Granatelli's Mass Airflow (MAF) sensor to improve airflow, have less pressure drop than production models, and have an expanded dynamic range with high measurement accuracy. It does this with no electrical modifications and uses a simple bolt-in design. Also, the inlet tube has been engineered to be smoother than the stock one it replaces to assist in airflow. Our baseline dyno run yielded 237 hp, which isn't bad for an absolutely stock '01 GMC 5.7L pickup. After we installed the Granatelli kit, the truck registered close to 248 ponies, 11 more from bolt-on parts-not bad at all! You might get different results, but even without being on the dyno the "seat-of-the-pants" feel was definitely impressive compared to the way the truck drove in stock form. Something to consider is that, according to Granatelli Motorsports, this package is sure to increase the effectiveness of other performance equipment already installed. In other words, we saw a nice gain in a stock vehicle, but that gain may be larger if other aftermarket equipment has been added. Follow along as we show you how to pick up easy power. Here's the fun stuff laid out on the shop floor as it comes out of the package. Remember todisconnect the battery before doing anything else.Here's the fun stuff laid out on the shop floor as it comes out of the package. Remember t For a more detailed look, here's Granatelli'sdiagram, part number, and list ofcontents. It's way better than the drawings you get with the kid's bicycles you're trying to put together at midnight on December 24.For a more detailed look, here's Granatelli'sdiagram, part number, and list ofcontents. It Starting at the throttle body, remove all of the GM factory intake ducting and the filter box. Underneath the factory airbox are 2 (each) 20mm bolts. Remove and use them to install the backing plate/shield assembly supplied with the kit.Starting at the throttle body, remove all of the GM factory intake ducting and the filter Compare the factory air intake ducting (top) to the new model (lower). Use the factory throttle body coupler to install the new air intakeducting.Compare the factory air intake ducting (top) to the new model (lower). Use the factory thr Install the factory MAF coupler over the plastic end of the Granatelli- supplied MAF sensor, and clamp in place. There is one more coupler. Install it and the filter adapter (supplied with the kit) over the opposite end of the MAF sensor. Then, install through the flaps in the shield and clamp in place.Install the factory MAF coupler over the plastic end of the Granatelli- supplied MAF senso Insert the completed assembly through the flaps in the shield, from inside the shielded area behind the headlight. Once the intake tube is inside the coupler/flap assembly, clamp in place.Insert the completed assembly through the flaps in the shield, from inside the shielded ar Plug in the MAF sensor and install the filter supplied in the kit to the filter adapter. Secure it with a clamp. Remember to affix the supplied SMOG label to let any testing technician know that the equipment is certified 50-state legal.Plug in the MAF sensor and install the filter supplied in the kit to the filter adapter. S Check all clamps and connections, and head for the dyno. If you don't have one, enjoy the test drive.Check all clamps and connections, and head for the dyno. If you don't have one, enjoy the SOURCES Granatelli Motorsports 18551 Topham St., Unit J Reseda CA 91335 818-996-2753 www.granatellimotorsports.com Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!