For my mild street truck, I went with the #530722
It is the quietist of all the Flowmaster series
It has a 3" inlet and dual 2.25" outlets
High Performance Street, Truck & RV
The 70 Series Big Block II™ is designed around a large Flowmaster case for maximum volume and efficiency. The case is also 2" narrower than Flowmaster's original Big Block™ muffler, making for easier installation in tight applications. The 70 Series offers a mild mellow exhaust tone and incorporates a Resonant Tuning Chamber for reduced interior sound levels.
For additional 70 SERIES specifications: