• The Flowmaster 40 Series Muffler takes the checkered flag as Flowmaster's most aggressive-sounding muffler
  • Quality Flowmaster muffler crafting uses aluminized steel for corrosion resistance and precise mig welds for maximum durability
  • The Flowmaster 40 Series is highly recommended for early muscle cars, off-road and race vehicles and dual-exhaust rides
  • Hear the power of your engine with the excellent interior resonance of the 40 Series—especially at 1800-2000 RPMs and again at 2400-2600 RPMs
  • Original two-chamber design maximizes horsepower and torque
  • The centerpiece muffler for many Flowmaster American Thunder Exhaust Systems
  • Casing embossed with the Flowmaster name
  • Your Flowmaster 40 Series Muffler carries a 3-year warranty

 
40 Series American Thunder Standard Universal Muffler
40 Series American Thunder Standard Universal Muffler
From: $72.93
 
Part NoApplication
42441Flowmaster Inlet/Outlet: 2.25" IN (O) / OUT (C): ea 40 Series American Thunder Standard Universal Muffler
42443Flowmaster Inlet/Outlet: 2.25" IN (O) / OUT (O), Mustang Muffler 40 Series American Thunder Standard Universal Muffler
42541Flowmaster Inlet/Outlet: 2.50" IN (O) / OUT (C): ea 40 Series American Thunder Standard Universal Muffler
42543Flowmaster Inlet/Outlet: 2.50" IN (O) / OUT (O): ea 40 Series American Thunder Standard Universal Muffler
430402Flowmaster Inlet/Outlet: 3.00" IN (C) / OUT 2.50" (D): ea 40 Series American Thunder Standard Universal Muffler
43041Flowmaster Inlet/Outlet: 3.00" IN (O) / 3.00" OUT (C): ea 40 Series American Thunder Standard Universal Muffler
43043Flowmaster Inlet/Outlet: 3.00" IN (O) / 3.00" OUT (O): ea 40 Series American Thunder Standard Universal Muffler