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Exhaust size 93 3500

2.5" with a lot of pinch on the Down Pipe, makes the effective diameter less than 2.5".

I am not sure if anybody have measured the effective diameter which is the smallest diameter on the pinch portion of the exhaust.

There are a few pictures on the pinched Down Pipe in the 6.5 TD forums arund the net.
 
I love the sound of the straight piped Diamond Eye system.
Later I found the tail pipe tip that came with the system, stuck that on and that made quite a difference in the tons of the exhaust.
I think that the tone could be altered by moving the tip deeper or shallower onto the tail pipe.
 
If you are doing any upgrades- larger exhaust is one that helps. 4” is the preferred go-to.
Obviously epa/ emmisions rules in your area are always to be looked at. So most guys here keep the old soot trap and muffler on a shelf just in case they get a request to return it to stock. Then they add mufflers/ resonators to preference- young dudes usually just pipe while guys like me that had enough of that noise add the stuff to tone it down.

Is diamond eye stuff still available- I thought i heard they weren’t making the kits for these rigs anymore?
 
I must have gotten lucky when I ordered my diamond eye exhaust kit from summit. after I bought it apparently they quit making them.

after installing, I could never get the tail pipe to line up right going around the back side of the rear tire so I chopped it off about 12 inches or so back under the truck and clamped a 4" to 6" tip on there. it sounds good, but it does get annoying going on long trips with the noise resonating into the cab. my kit has the muffler included but when installing it, I noticed that it's just a 4" perforated pipe with no baffles encased in a 6" pipe about 36 inches or so long. maybe later on I may look at doing something to quiet it down without harming the free flow.

I'm curious if just simply using a different tip can make it quieter or change the deep tone to something better for the ears lol

after installing mine, I did notice the extra oomph from the truck but no mileage increase. I think that was mostly due to my foot though lol
 
the crossover pipe just flows exhaust into the other manifold where the turbo is. a leak or broken crossover can harm your mileage by not allowing your turbo to function at it's full potential. most of the piping after the down pipe is straight 2.5" through the soot trap up to the muffler. you should be able to pick up a section of straight 2.5" and a couple of couplers, a few u-bolt clamps. this will allow you to chop the soot trap off and run straight pipe down to just before the muffler.

for low noise level I wouldn't recommend a axle dump, the exhaust resonating from the road will make it loud in the cab. it also can cause cause a bit more exhaust back pressure as the air from the tail pipe flows out and "hits a wall" at the ground. it the pipe is curved out behind the rear tire or piped straight to the back bumper it will flow freer and be quiet.

when I bought my truck, the PO had chopped out about a 12" section of pipe just behind the soot trap leaving it open under the cab. the muffler and tail pipe was all still intact. for the life of me I never figured out why he had cut it there, but I finished it off by removing the soot trap and re-connecting the muffler so it would pass state inspection.

if your going to spend some money on the exhaust, go for the 4" kit. it's fairly easy and straight forward to install. Just get a muffler to quiet down the noise.
 
Yup- check that tps. Check the linkage is ok- seen it before where someone adjusted it wrong, but rare.

The cross over goes from driver side manifold to the passenger side manifold where the turbo is.

Most of the things guys do to the truck is for longer life, a little more power and little more mpg. Replacing the exhaust with better flowing one is help on both power and mpg. 3” is good. 4” is better- but you decide cost obviously.

Below is the current problem- but do soon after buying:
Spend free time reading the stickies. That knowledge in their will save you thousands over time as well as a bunch of time when the issues pop up.

Have you already checked your oil cooler lines and harmonic balancer? Both are engine killers.
Make sure your temp gauge is reading accurately. 195-200 normal. 210 watch the gauge more than the road and 220 pull over and let it idle back to normal. A bunch of junk out there even from the military these engines are ok to 230 or even 240- but they don’t get 70,000 miles from a 6.5 before they are messed up.

Short term do the wif valve test to make sure you have fuel pressure to the ip when running. Longer term get a gauge on there you can read while driving. Low fuel pressure into the ip wears it out quickly, and the engine will run without a good lift pump.
 
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