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.