<!-- / icon and title --><!-- message -->I posted this on the exhaust forum also, thought I might get more hits here.

I have a 89 F350 with a 6.9 which has 5" stacks. They are way too loud, it is a standard cab and if I drive over 55 my ears are ringing. I found the stack inserts on the internet and was wondering if anyone has tried them and if so how much would they help? Here is the web link.
Quiet Muffler Insert for 5" Stacks - IOWA80.COM

Are there any othere options out there? With the standard cab there isn't room for a muffler.
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So i had the same problem and while it was a home brew fix, it worked like a champ, took all the loud rap out of the pipe, and i dont mean t pain. lol. It is essentially a custom baffle or resonator. My pipe leading up to the stack is 4" so i removed the stack and welded on the piece that looked like this...PIC ONE...



Then i installed a "cap" on top of that to seal it, i had 5" ID stack pipe so i had a machine shop make a ring for me out of 1/8" steel. half inch wide around the ring so as to cover the gap. Didnt need to weld that in place as it was really snug. So what i did was make a chamber to catch the exhaust and chop up the noise a bit and it really worked. Just make sure it is the right way, the indents should be "catching the flow," Cost was 15 for the machine shop to make the ring, and 20 for pipe. The rest of what i needed was on hand like welder, side grinder with cutoff wheel, and patience. The inside looked like this...PIC TWO...



I just cut a bunch of tees in a spiral pattern going up the pipe and then the horizontal lines and folded the parts in with a punch and hammer.

If you need more details or just want to wait for other opinions go ahead but this works very well, you could stuff it too with fiberglass for more sound deadening but i couldnt find any. No biggie. Best luck bro.

 

Thanks that is awsome!! How much of a difference did it make?

 

alot man, alot. If i wasnt cracking welds from my initial welder being crap i woul dhave kept it in place. But without the mod, i was ready to toss it. Just too much noise. With the mod it is a nice deep tone but nothing crazy.

 

They are so noisy I've been thinking about yanking them off. Last night coming home from work I passed a truck with either a 6.9 or 7.3 IDI with stacks on the highway doing about 65, I was driving my F150 so I could hear it. I pulled up beside it and all I could here was the tires, it was quiet. How did he do it. I would have liked to talk to him!!

 

one of two things, he either has a large muffler(probably the cause) or a combo of the muffler and stack baffles. They work well bro if installed properly and a good open chamber muffler is used, like the all metal baffle flowmasters. They really cut out the high noise levels. leaving the rumble only.

 

Thanks alot for the info wreckinball, I appreciate it!!