454cid
Sooper Pooper
Hate to tell ya but dual 2.5s do outflow single 3 but unless you have the power to use the additional area it dont matter. Get exhaust off a 97 or truck and they true duals to the muffler and if its a 2500 or 3500 it has big exhaust almost 3" duals to the back with dual in dual out muffler
Almost..... It drops down to about 2.75 before the muffler and exits as a single pipe. I still have the stock system on my K3500.