The level above our Performer Series® Carburetors is our Thunder Series AVS®. Manufactured and calibrated for optimal street performance in hundreds of situations, Edelbrock Thunder Series AVS® Carbs are without doubt the most cutting-edge and reliable street performance carburetors on the market today. Primary and secondary booster clusters deliver the most accurate and current calibration on the market for modern fuels and octane levels. The Thunder Series' unique Qwik-Tune Secondary Air Valve provides for limitless calibration of the secondary circuit by using regular hand tools without dismounting from the vehicle. Quick. Simple. Effective. This permits adjustment - in seconds – for your specific situation. There are no extra parts needed to achieve optimal performance.