I am thinking of putting the Magnaflow 15609 on my truck along with all the usual bolt ons; cold air, chip etc.... My concern is 3" tubing too large on a other wise stock engine? I'm more interrested in TQ for pulling power. Would I lose too much TQ in the mid range while pulling a trailer, say, up hills and the such?
Mid range power/ torque and fuel mileage are my main concerns. Any info would be greatly appreciated. Thanks

 

Souldn't have any problem with it on the 4.6. The Super Dutys have 3 inch on the 5.4 stock from the factory and only one cat.

 

You should be fine with a single 3" pipe. This is excellent for "pulling" power.