If you have the Vortec LQ4 engine, our information indicates that it is a cast iron block with aluminum heads. This is a common configuration in the GMC high-performance V8 family and is fully compatible with the Berryman Professional 3-Step Fuel System Maintenance Kit (part #2630). Unless your air-intake and fuel systems are already clean, you should notice an improvement in idle smoothness, responsiveness, power, and gas mileage, especially if you change spark plugs. If you’re running stock plug wires still, you might also consider upgrading to low-resistance 8.5 mm wires, too. Good luck!