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Manufacturer information. Check the part number and installation requirements for your vehicle.
Supplier details checked 2026-09-23 · Test catalog
Fits 1967-1970 Ford Mustang with V8 engine. Stainless Steel. - Aggressive to moderate sound
Flowmaster American Thunder Crossmember-Back Exhaust System
Does Not Include Header Reducers or Downpipes for Factory Manifolds
Super 44 Series Performance Mufflers for Deep Powerful Sound
Includes Hangers and Hardware for Installation
Mandrel-bent 16-gauge Stainless Steel Tubing
Aggressive to Moderate Exterior Exhaust Tone
3.00-inch Polished 304 Stainless Steel Tips
Crossmember-Back True Dual Exhaust System
H-pipe Crossover for Maximum Power
Lifetime Limited Warranty
Fits 1967-1970 Ford Mustang with V8 engine and exits through rear valance exhaust cutouts. Does not fit convertibles or staggered shock models.
Flowmaster 67-70 Mustang American Thunder THRU VALANCE SS Crossmember-Back Exhaust System
6770 MUSTANG AMT THRU VALANCE 409S
SYS 67-70 MUSTANG AM
For the person who is looking for a true dual Crossmember-Back exhaust system with an moderate to aggressive exhaust tone. With an easy fit in mind, these systems are constructed from 16-gauge mandrel-bent stainless steel tubing with a built-in H-pipe crossover, a pair of specially selected Super 44 Series mufflers and includes all hangers and hardware necessary for installation. This system fits through the factory rear valance exhaust cutouts and includes a pair of 3.00-inch polished stainless steel tips. The American Thunder systems deliver a moderate to aggressive interior and exterior tone and are best suited to the enthusiast who wants their performance to be heard. Like all Flowmaster exhaust systems, the benefits include improved throttle response, power and mileage. If you prefer aluminized steel construction, check out optional system# 17281. Notes: Does Not fit convertibles or cars with staggered shocks. Does Not include header reducer cones or downpipes for factory manifolds.
SYS 67-70 MU
