jsack12

so I'm doing some new exhaust setup to my truck. When I'm done this is how it will be set up
- off manifolds to the first cats then rear cats are removed with straight pipe then to the stock y pipe and then after the y pipe it will exit out in front of the rear pass tire. It will be single pipe off the y pipe then curve and connect to a 1 to 2 adapter with the tips clamped to that to give me my dual tips I want. My question now is what size diameter pipe do I wanna do off the y pipe all the way through to the tips? I red somewhere that if I stay in the 2.5" range that it will keep good back pressure and keep the system tight from throwing a code. But if it does throw a code then I'm not worried because I can do the gotts mod or tune it and get it deleted. But according to this forum link I found online specific to the exhaust for these trucks it says to do 3"

http://www.f150online.com/forums/exh...ust-guide.html

Let me know what you guys think I should do and what we be the best performance/ fuel mileage and all that wise. There is also a chance in the future of putting a high flow muffler in line of that somewhere depending on how I like the sound

nof3ar

I'm looking to throw up hooker chamberd muffler in there tomorrow but right now after cats it's a 3 inch pipe but after the muffler it's 2.25 opening up to 2.5 with a flow 50 series. I been doing a lot of reading on pip diameter and found you can't get a straight answer. So my conclusion is threw what u want on there, as long as your not doing so thing big your ok. Iv concluded at 2.5" pipe u have low end torque but loose upper end torque. Bigger pipe u have higher end torque.

If it floats your boat, go with it!

Carcrazygts2

Back pressure is a myth. Dont go bigger than 2.5"

Krack499

iTrader: (1)

Oops I messed up then with my 3" duals lol

TLB4

Don't worry, I'm running a 4" straight pipe to a 6" tip. I apparently messed up more.

jsack12

So still no certainty here.

Carcrazygts2

I bet you guys both have factory manifolds and cats too. I can tell you where the it important for pipe size is the first 18" after the manifold. It will determine where and when power is made. Too big an it will kill bottom end tq due to loss in scavenging.

Krack499

iTrader: (1)

Yep factory manifolds and cats all 4 at that

Carcrazygts2

So really you dont have 3" duals. You still have 2.5". I have full 3" with longtubes and it makes a huge difference where power is made.
[MENTION=40021]jsack12[/MENTION] Stick with 2.5" to the factory y-pipe. After the y-pipe you can step up if you'd like.

Krack499

iTrader: (1)

It's 3" true duals after the cats