I'm about to cut off my stock muffler, before I do so I'm Guna buy a glasspack. What inlet/outlet size do I need? 1996 f150 i6 4.9. Thnx guys

 

I think it should be 2 1/4" if its stock, easy way to tell is wrap a piece of string around it and then measure the string. I'm putting my glasspack on today, but I had to buy some adapter sleeves for it cause they only had certain inlet/outlet sizes for the length I needed.

 

Measuring with a string wrapped around the pipe would give you the circumference. You'd have to divide that by 3.14 to get diameter. Easier to measure top edge to bottom edge and get the diameter.

 

The O.D of my pipe cat back was 2 1/4". So I just bought pipe to slide over it.

 

Yeah I wasnt quite awake yet this morning when I wrote that, lol... You are correct sir..