40 Series Delta Flow Muffler

The Flowmaster 40 Series Delta Flow Muffler is a universal bolt-on exhaust silencer engineered for street and performance applications where you need genuine sound control without sacrificing flow. Designed by one of the industry's most respected manufacturers, this muffler suits hot rods, muscle cars, and modified trucks looking to dial in a deep, aggressive tone while maintaining backpressure efficiency across the RPM band. The 2.5-inch offset inlet and center outlet configuration makes it a drop-in solution for countless custom exhaust builds where space or mounting angles demand flexibility.

Built with steel construction and finished in durable black paint, the 40 Series Delta uses Flowmaster's proven Delta Flow chamber design to reduce noise levels through multi-stage absorption and tuned internal passages rather than restrictive packing materials. The 13 x 9.75 x 4-inch oval body (19 inches long overall) balances compact mounting footprint with adequate volume for low-frequency sound attenuation, while the center outlet allows you to route exhaust exit to suit your chassis layout. At 10.45 pounds, the muffler adds minimal weight compared to factory units, and the steel composition delivers proven longevity in both street and mild performance environments.

Mechanics and enthusiasts favor the 40 Series Delta for custom exhaust systems on 2.5-inch piping setups where universal fitment is required—common on LS-swapped vehicles, engine transplants, and home-fabricated exhaust work. The offset inlet design accommodates tight engine bay layouts and transverse mounting positions that would reject traditional center-inlet mufflers. Installation requires basic exhaust hanger and clamp work; confirm 2.5-inch pipe diameter and outlet clearance to your chassis before ordering. For vehicles running stock or mildly modified engines, this muffler delivers the aggressive Flowmaster character without the extreme sound levels associated with open headers or high-flow racing cans.