pipe sizes

[Dangeranger3]

I need to put some exhaust back on my truck so I need to buy a muffler. But I'm not sure on the size to get. Does the pipe go by the outside diameter or inside? I just bought an "intermediate pipe" to bolt up to my cat and need to know the size muffler inlet to get. I measure 1 and 3/4 inside or a hair under 2" outside. I'm guessing that a 2" inlet on a muffler would work but want to know before I spend the money. Thanks in advance.

[85_Ranger4x4]

Here is a pretty good rule of thumb that I went by when I put duals on my F-150. I think exhaust pipe is OD, my 2.25" tips were oversized to go on the 2.25" pipes.

http://www.magnaflow.com/07techtips/faq/question10.asp

[Hahnsb2]

OK, lets say you are running 2 1/2" pipe you would buy a 2 1/2" muffler, which will be expanded to the correct size to fit over 2 1/2" pipe snugly. Thats pretty much how all exhaust components work.

[Dangeranger3]

Great thanks for the info Hahns and 85 ranger. What Hahns wrote is exactly what I wanted to hear.