Ramcharger exhaust 2-1/4 duals or single 3"

I would think the 2 cats would represent the greatest restriction to create back pressure. How many cell are they? Most emission replacement are 600 cell. Switching to 3" post cat probably won't do anything. I think a wide band and tune on the carb would be the next move I would make if this mine to champion. Going from 9 to 13 is commendable but to a point the weight, aerodynamics and efficiency of the trans, transfer case (?), front and rear end become a power absorber.