So, I have an 07 E350 with a 5.4.
I've been thinking about running a 4" exhaust from the y pipe back with a FlowPro straight thru muffler (Was to be for my 5.9 Dodge Diesel)

Any ideas if this would be of ANY benifit other than noise??
Thanks

 

I don't see it becoming a benefit other than noise. I have my 5.4l with dual 3" and it is hard to notice unless you have other mods done with it. look at what 5 star performance sells for these trucks or any other company with satisfied customers it is more than just exhaust. .You will likely need to bolt on some of the same components to see a benefit. As far as MPG you will have driver mod to increase your mental strength to resist putting your foot in it. I do enjoy the programmer I have with a email tune because the converter is locked up more.

 

I think you'll actually lose performance. That's a big drop in back pressure. Non-forced induction vehicles need back pressure to efficiently scavenge exhaust gasses from the cylinders.

 

Close but no cigar. "Back pressure" will sent exhaust BACK into the cylinder. What is lost with a too-large exhaust is velocity and the scavenging that you can gain with proper exhaust "tuning". If you pump it into a big pipe it tends to want to sit there, vs. keep moving and drawing other gas with it.

Performance and road car exhaust

Exhaust: The straight scoop on backpressure | DSMtuners

 

Yes I should have had this right since I posted an article on it way back. This is what I get for drinking and typing!