I need a little advice on what kind of mufflers I should put on my '91 f-250 7.3L diesel. It currently has single exhuast and the pipe is small, I'm guessing 2 1/2" or 2 3/4". I am going to go with true dual exhuast in 3" pipe and I was just wondering what brand and type of muffler would be best. If it matters, I am more concerned with improving air flow than sound but a better sound would be nice too. Thanks!

 

no muffler at all is what most people do.

 

some of us would get pulled over and written a ticket for having no muffler.

 

The natural aspirated diesel does make a bit of racket with straight pipes.
I always go for a see through muffler, that keeps restriction to a minimum but does help with the sound some.

On a turbo motor, no muffler is needed, the turbo does a good job leveling out the exhaust pulses.

 

i have a 91 250 7.3 4x4 and am having a hard time finding aftermarket parts for it.there seems to be more available for the 93 s and up.i want to replace the exhaust and air intake .bigger exhaust then the stock and better air intake.i know banks will sell there ehhaust seperatly from the sidewinder kit,its 31/2in,would like to go to a 4in if possible.any help on locating parts would be appreciated.thanks Don

 

Don,
First let me welcome you to FTE and the IDI diesel forum.

Unfortunately there is not a lot of aftermarket goodies for the IDI diesel.
They just kinda forgot the grandfather of the modern Power Stroke.

For the non turbo motors you have to come off the manifolds with 2.25" ID pipe, bigger will not seal to the manifolds or fit the clamp.
Where most people are making the change is under the truck cut the Y apart so each downtube from the manifolds dump into a 3" pipe where they go together. Big improvement in air flow.
Several people here have also run dual 3" exhaust, but getting the drivers side pipe around the front fuel tank is a pain.
If you stay with 3" pipe a lot of muffler shops can bend the exhaust for you.
Very few can bend 4" pipe, but there are a few if you happen to be lucky.
As far as muffler, go with the least amount of restriction you can stand, the noise will go up with the see through variety, but they also are the best for the power output level.

For an intake, I made my own ram air.
Cool air that is under pressure while you are driving at highway speeds is a good thing.
Links to my intake,
https://www.ford-trucks.com/user_gal...100511&width=2
https://www.ford-trucks.com/user_gal...100545&width=2

 

Don, I have dual 3inch exhaust and I am very happy with them. The muffler shop ran both pipes side by side up and over the axle. I tow a 5th wheel...I had single 3inch exhaust before going dual, I didnt expect too much but what I got was a cooler running IDI with a lot more pulling power, able to run higher rpms...the engine has approx 175,000 miles on it. Check out Daves ram air intake, these IDIs love air and if your thinking of going turbo, go single 4inch. All in all you can not go wrong with bigger exhaust. lol