Would a 3 inch magnaflow muffler and piping be worth it or should i stay with the factory 2 1/2 inch piping. the truck is a 97 f150 supercab with a 4.6L. I don't want to lose torque beacause i tow a trailer. which one would compliment my K&n fipk better. thanks for any help.

 

If your gonna run SIDO I can't see you losing any low end, and it will make your truck sound a little deeper as well, I'm not so sure about running SIDO with 3in Pipes.

 

I think the 2 1/2" would be a better choice. If your running duals I would go with nothing over 2 1/4". Alot of people make the mistake of running to large of an exhaust for the availble HP. From what I have seen a strong 4.6l makes about 170 to the wheels, 2 1/2" can support around much more than that IMO. Here is a small article about exhaust tubing.....

Most of the time bigger is better, but that's not always the case with exhaust. Today's late model cars are designed with several restrictions on the manufacturers. So in order to perform but still stay within the limits of emissions and other regulations, the exhaust is usually the first thing to suffer from the factory. The easy power that is found in changing the original equipment exhaust system, is just one of the many reasons there are so many aftermarket manufacturers capitalizing on this insufficiency. But just opening the exhaust doesn't always make more power, it takes the correct combination of flow capability and velocity. That's why performance exhaust manufacturers spend so much time in search of just the right combination, so that they can ensure peak power to their customers.

In this article we will discuss the effects that exhaust backpressure has on your engine. Backpressure is the restriction of the exhaust gases that are produced by your engine while they are being released through your exhaust system. Exhaust gasses are the burned and unburned gasses that are released out of the exhaust system after engine combustion happens.

The exhaust system should have minimal restriction to the exhaust flow that is being released in order to create the most amount of power from the engine. With restriction present, backpressure is developed, making the engine work much harder to release the exhaust out of the engine cylinders.

The standard for exhaust diameter is to not run too large of exhaust, for the engine needs a certain amount of backpressure. This is correct in the sense of one should not run too large of diameter exhaust tubing, but the statement of the engine needing backpressure is not. You need to have the least amount of backpressure possible to produce maximum power. Too large of diameter exhaust will cause a power loss and loss of low end torque because a larger pipe has less exhaust stream velocity than a smaller pipe. If the exhaust pipe is too large, then the exhaust flow will be slowed with less velocity. There are exceptions, forced induction or high-volume race engines require a larger diameter exhaust due to the flow characteristics of the engine. Supercharged and turbocharged vehicles can have an exhaust gas volume of 1 to 2 times more than an equivalent displacement naturally aspirated engine. In this case, one is able to use a larger diameter of exhaust for greater performance.