What Size Muffler Fits 1998 Ford F-150 4.6L V8

The Ford F-150 is a popular pickup truck that has been in production since 1948. The 1998 F-150 with a 4.6L V8 engine is a commonly owned model and when its time to get a new muffler, you need to know what size to order. This article discusses in detail the sizes of mufflers you can use that will fit your 1998 Ford F-150 truck.

A 2.5″ muffler fits a 1998 Ford F-150 4.6L V8 truck.

The 2.5″ is the most common size for a muffler on these trucks but there are 2 sizes of pipes that it could have that you need to consider, the 2.5″ which is the most common and the 2.25″ which is less common. Chances are that your F-150 has the 2.5″ pipes, but let me tell you in which case it would be 2.25″.

The 2.5″ Exhaust Pipe = Y-Pipe

The 2.5″ exhaust pipe is common in trucks that have a Y-pipe going into a single pipe going to the back. Since both sides of the engine exhaust is meeting in the Y-pipe into one, the pipe needs to be larger to accommodate all that exhaust. So if you look under the truck and see that you have a single pipe going to the back of the truck, it is most likely 2.5″. This means you need to get a 2.5″ muffler.

The 2.25″ Exhaust Pipe – True Dual Exhaust

This one is smaller in diameter, and is used in trucks that have true dual exhaust. This means that each side of the engine has a dedicated pipe going all the way back with its own muffler. Since it is not sharing space with the other side of the engine’s exhaust, the pipe doesn’t need to be as large. If you look under the truck and see that you have an exhaust pipe on each side of the truck, or 2 pipes going side by side from the engine all the way back, they are most likely 2.25″ pipes. This means you will need 2 x 2.25″ mufflers.

1998 Ford F-150 Muffler Size Refference Table

Exhaust Type	Muffler Size
Y-Pipe	2.25"
X-Pipe	2.25"
True Dual Exhaust	2.5"

Converting Pipe Sizes

Because the size of the pipes are engineered to be just the right size for the application, it is not recommended to be messed with. But this is your truck so if you want to you can put a 3″ exhaust pipe on it! This doesn’t mean you will get the maximum performance out of the truck, but it will look cool and also may sound cool.

If you decide to go from a 2.25″ to a 2.5″ pipe, it will not be a big deal, in fact, many people do that, and also 2.5″ to 3″ is also not too big of a deal. To do this you will just need to get some pipe adapters for a few bucks.

The Bottom Line

Look under your truck. If you see 2 pipes going all the way back, without the Y-pipe in the front, you probably have a 2.25″ exhaust. If you just have 1 pipe, it is most likely 2.5″. You can also use a caliper tool to measure the outside diameter of the pipe to know for sure.