Enter Garage
Representative imageManufacturer information. Check the part number and installation requirements for your vehicle.
Supplier details checked 2026-09-23 · Test catalog
Fits 1964-1967 GM A-Body 3.00-inch stainless steel system with V8 engine. - Aggressive sound
Flowmaster American Thunder Crossmember-Back Exhaust System
Large 3.00-inch Exhaust System for High Horsepower Engines
H-pipe Crossover for Maximum Power and Deep Tone
Super 40 Series Mufflers for Deep Powerful Sound
Includes Hangers and Hardware for Installation
Mandrel-bent 16-gauge Stainless Steel Tubing
Crossmember-Back True Dual Exhaust System
Aggressive Exterior Exhaust Tone
Lifetime Limited Warranty
Does Not Include Header Reducers or Downpipes for Factory Manifolds
Flowmaster 64-67 GM A-BODY 3in. American Thunder SS Crossmember-Back Exhaust System
6467 GM ABODY 3 AMT DOS 409S
SYS 64-67 GM A-BODY
The American Thunder® Crossmember-Back exhaust system is a true dual large 3.00-inch muscle car system for the person who is looking for a deep aggressive sound for their high horsepower vehicle. This stainless steel system is mandrel-bent for maximum performance, includes an H-pipe crossover to balance out the exhaust pressures, add hp and torque, and to help eliminate back-rap on deceleration. The specially selected Super 40® Series performance mufflers feature a large case to handle the added horsepower and provide a deep muscular tone flowing through the large 3.00-inch tailpipes. The American Thunder systems generally deliver an aggressive interior and exterior tone and are suited to the enthusiast who wants their performance to be heard. The sound level will depend greatly on the engine and level of modifications. Like all Flowmaster systems, the benefits include improved throttle response, power and mileage. Designed for an easy fit, these systems include all necessary parts and hardware for easy installation. Covered by our Lifetime Limited Warranty.
SYS 64-67 GM
