I swore i was going to leave my truck stock, but im thinking that im only going to add 2 things, a cold air intake and a better sounding muffler.

but i need to know the stock exhaust diameter so i can go get my flowmaster, it's a little chilly out for me to go look (-40*C) so i would apprecaite any info thanks in advance

p.s. im thinking it's 2.5"

 

2.5 is correct. The flowmaster has a 3" inlet/outlet, but you can still get it welded on just fine. Mine is exactly like that. 2.5" piping welded to a 3" inlet on the Flowmaster. Works great too!