Hey Darren, I know you have this answer. What is the diameter of the pipes coming from the cats before the Y-pipe on an '05 5.4l? I am piecing together my exhaust and I am looking to pick up a Maggie Y-pipe from summit. I wanna say 2.5 but I just need to be sure before I place the order. My *** could measure it myself but there is snow on the ground here in Philly. Thanks!

 

2 1/2

 

Yep its 2.5". Your entire exhaust is 2.5", though the stock tailpipe is 2.75".

 

thanks you guys.