We're all in search of the perfect combo, the right mix of parts and tuning to endow our rides with the properdose of high-performance fun. The process is especially satisfying when the payoff results from our own long hours of research. On the other hand, there's certainly something to be said for letting someone else do the homework. With this idea in mind, we decided to check out one of SLP's PerformancePacs, using an untouched '04 Avalanche as our test subject.
SLP has a PerformancePac for just about anything running a Gen III powerplant: '98-02 Camaros and C5 Corvettes, along with most trucks and SUVs. These packages come in variations for 4.8-, 5.3-, and 6.0L engines. The Avalanche system is a fairly new addition to the lineup and has proved to be a hot seller. "The Avalanche is surprisingly one of our more popular kits," reports Brian Reese, SLP's director of engineering. "We sell three for every truck kit."
One attraction to a package deal like the PerformancePac is ease of installation, and the system we sampled scored well in this department. Superior Automotive in Anaheim, California, accomplished the job-including before and after dyno runs-in a mere half day. Having access to a lift certainly helped with the exhaust system swap, but all other parts of the install can easily be done in the driveway
 |  Ditching the stock 1.7:1 rocker...  Ditching the stock 1.7:1 rocker arms in favor of 1.85:1 pieces (right) adds approximately 0.040 inch lift to both the intake and exhaust side of the Avalanche's very mild cam. SLP includes Allen bolts to replace the original 8mm hex bolts. |  Removing the stock manifolds...  Removing the stock manifolds on our subject Avalanche wasn't difficult. You may find it easier to remove the driver-side piece from the bottom of the vehicle, but our guys were able to pull both out from the top. All in all, the stock Avalanche pieces aren't bad for stock manifolds, but SLP's coated shorty headers are still an improvement, and they look pretty slick too. |
 In short order, the factory...  In short order, the factory air-intake rigmarole was removed. The black plate that sits beneath the stock airbox (arrow) must be removed to allow installation of the new airbox. |  Compared to the original setup,...  Compared to the original setup, SLP's Cold-Air Induction System looks pretty simplistic-and it is. Installation is equally easy, and again we'll just touch on a few highlights. |  The new airbox bolts in using...  The new airbox bolts in using three of the five bolts that held the plate in place. Installing the new high-flow filter element requires a little finagling to work it into place. With an open side and bottom, the SLP box allows much more outside air to reach the filter. |