Free shipping on ALL orders!* - Details
1968-70 Mopar B-Body - 2.5YouTube Button

Flowmaster American Thunder Header-back Exhaust System

1968-1970 Mopar B-bodies with V8 engine. Stainless Steel

PART# 817390

Be the first to write a review
$836.00   Suggested Retail
$751.95   Holleydays Price
Free Shipping
In Stock  
Add to Wish List

Starting at $67 a month with Learn More
Aggressive to moderate sound


The American Thunder system is for the person who is looking for a complete headers-back dual exhaust system with a deep powerful sound. The system is constructed from 2.50-inch mandrel-bent stainless steel tubing and includes an H-pipe to balance the exhaust pulses and to eliminate back-rap on deceleration. The large cased Super 40 Series performance mufflers generally deliver a moderate interior tone with a deep powerful exterior sound which is suited for enthusiasts who want their performance to be heard. The mandrel-bent tailpipes exit straight out the back under the rear bumper for a strong muscular appearance and allows you to select your own style of tips. Designed for an easy fit, these systems include all necessary parts and hardware for easy installation and is covered by our Lifetime Limited Warranty. .


  • H-pipe Crossover for Maximum Power and Deep Tone
  • Super 40 Series Mufflers for Deep Powerful Sound
  • Mandrel-bent 16-gauge Stainless Steel Tubing
  • Includes Hangers and Hardware for Installation
  • Moderate to Aggressive Exterior Exhaust Tone
  • Header-back True Dual Exhaust System
  • Does Not Include Header Reducers
  • Lifetime Limited Warranty


Automotive Item GradeHigh Performance
Emission Code3
Exhaust Pipe Wall Maximum Gauge16
Exhaust SeriesAmerican Thunder
Exit PositionDual Out Rear
Heat ShieldNo
Inlet Diameter (in)2.5
Material409 Stainless Steel
Mount TypeUses New Hangers (Included)
Muffler Quantity2
Muffler SeriesSuper 40 Series
Outlet Diameter (in)2.5
Product TypeExhaust System
Single DualDual
Sound LevelAggressive / Moderate
System TypeHeader-back
Tip Diameter (in)2.5
Tip ShapeRound
Tubing Diameter (in)2.5
California Proposition 65 Chemical NameChromium (hexavalent compounds)
Nickel (Metallic)
California Proposition 65 RequiredYes
Part Number817390



This part is legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles and Racing Use Only Vehicles.

The following vehicles are considered Uncontrolled (Non-Emissions Controlled) Vehicles:

  • 1965 and older U.S. manufactured California Certified vehicles
  • 1967 and older U.S. manufactured Federally Certified vehicles
  • 1967 and older Foreign manufactured vehicle

The following vehicles are considered Racing Use Only Vehicles:

  • Racing Use Only Vehicles are vehicles that are used exclusively for competition and that are not registered and that may never be used on the street

WARNING: It is against the law to install this part on an Emissions Controlled Vehicle

The following vehicles are considered Emissions Controlled Vehicles:

  • 1966 and newer U.S. manufactured California Certified vehicles
  • 1968 and newer U.S. manufactured Federally Certified vehicles
  • 1968 and newer Foreign manufactured vehicle

Tech Resources

Does Not include header reducer cones.


We Suggest
    Also Bought

        *Free Shipping & Handling only offered to the contiguous US on orders over $100, excludes clearance parts and oversized packages.

        Some parts are not legal for use in California or other states with similar regulations.

         X  Holleydays 2020 20% off and DD
         X  Holleydays 2020 20% off and DD