The major differences between the products in the Flowmaster 40 Series and other Flowmaster Series are the exterior sound level, the internal resonance and the design configurations of the mufflers. You can purchase the Flowmaster's muffler from the series that best accommodates your desired external and internal exhaust amplification and fits with the size and configuration of your vehicle.
The Flowmaster 40 Original Series is ideal for customers who desire highly amplified internal and external exhaust output. The Flowmaster 40 Delta Flow, however, is the better choice for customers who desire optimized performance with less audible interior exhaust output and high external output.
Flowmaster has 11 additional series of mufflers that vary widely in size, material composition and exhaust output. The Super 10 Series, for example, is compact and optimized for racing, and is not recommended for typical street use. The 80 Series features a cross-flow muffler that Flowmaster recommends specifically for Camaros and Firebirds. In addition to external and internal exhaust amplification, the 80 Series cross-flow muffler also enhances torque and horsepower.
Most of Flowmaster's mufflers offer a choice of aluminized or stainless steel casing. The mufflers are welded with metal inert gas for optimized durability and are backed by Flowmaster's lifetime guarantee.