What size is the stock exhaust diameter on a 2009 3v v10? I'm a plumber so I know pipe size but it looks a bit shy of 3" like 2 3/4 if there is such a thing, I look under my work van which I had 3" installed and it looks bigger.

I just bought this truck, it has a magnaflow muffler and the stock pipe.
Even though I'm a Ford guy I had an 06 duramax till last weekend so I am looking to get more power out of the v10, diesel I don't use enough is why I changed plus GM trucks suck except for the duramax and allison, the truck was falling apart at 89k, love being back in a Ford again

 

Save the money on exhaust and look at headers and a tuner. Stock exhaust is usually around 3" though.

 

Its definitely a good bit bigger than 2.25". I bought a tip for mine with a 2.25" in and 4" out. I had to expand the "in" and hammer down the tailpipe....

Don't worry about an exhaust. It wont gain you much, if anything at all. Personally, I plan on headers and true duals for the simple "cool factor" but I know it probably wont gain me much. Your biggest gains would be from headers, a y-pipe (at the same time), and a tuner from 5-star. If your going to use your truck for towing, a lot of guys will tell ya save your money on everything and get yourself a set of 4.30 (or lower) gears

Glad to see you come back to Ford! A v10 definitely wont let ya down!

 

my truck already came with a magnaflow but I want to change it out to a dynomax vt, any advantage to going bigger like 3.5 (i noticed Banks is 3.5") I have seen a few guys running 4" like diesels, I'm not interested in headers as on a 3 valve theres not much out there and dont think it will make much difference, 5 star tuning is my next stop.
Mine is an 09 3v

 

I have a 4" mbrp cat back and a SPD y pipe. It sounds awesome when it starts up and when I get on it. With the cat back and y pipe it revs better but I think I lost some low end torque. The y pipe is better, I would save on the cat back changes though.

After seeing a couple header threads on here I honestly think those are the best bet with gears and custom tunes. I dont have a tuner yet but that may be on the list this summer. Just have to see how it all pans out.

 

I have an 09 3v 6.8L and I changed my exhaust today. The stock was 3 and I went to 2.5. I wanted to stay at 3 but the limited room was not allowing it. I went with the magna flow dual in/ dual out. It is louder than stock but not obnoxiously loud either. I like it so far and my next step will be a 5 star.

Chris