1987 300SDL Straight Pipe
 

Lately I've been really tempted to straight pipe my car. I have a good friend who would do the work for me, so that's not the issue. Plus I'm doing it mostly for sound. I know a lot of the purists probably aren't a big fan of taking out the refinement of these diesels. I've just been really tempted to do this for a long time now.

What are the pros/cons to straight piping this car? What do I need to look out for? Any advice would be great.

I've been running a 2.5" straight pipe from the turbo to the back for 5 years, sounds great, works great, low maintenance. :D

2cents
 

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cons; noise/droning pros: everything else

I will go with muffler only soon .....

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How does it sound at 70-80 MPH?

How about 110-115 where I frequently cruise on my 2 hour commutes???? I cannot imagine this car would run any harder and it has bone stock exhaust and dual mufflers...FWIW

My brother has been running a straight pipe on his Cummins TD for quite a while. The sound seems more in keeping with his D250 4WD than it would on a 126! I would think the only negatives to be the noise, and possible resonance issues.

Its hardly any different, no annoying drone or anything, at least not to me. The engine itself is louder at those speeds than the exhaust system.

The straight pipe does improve off the line torque slightly by allowing the turbo to spool/boost a bit faster.


I think the sound is awesome. :)

That's good to hear. Does it make a difference to remove the resonator? I was thinking about just straight piping it from the resonator back. Any suggestions on that? Unfortunately, I have to keep the CAT on for emission reasons.

Throw in an Exhaust Cut Out system, manual or electric, and you will be happy to control the noise whenever you want.
QTP » Electric Exhaust Cutouts

Perfect.

No noticeable increase in noise and less to maintain under the vehicle.

Just make sure the tail pipe makes it past the rear bumper. I had mine flush (on a w123) and the droning was insane.

I have 2.5" straight through a flow-through muffler only on my 300SD. It makes a nice deep rumble. I used the car for several days idling at 1,000 RPM to power an inverter during a power outage. The neighbors definitly know when the car was running, but then again they still would have with the resonaitor installed as well. I got no complaints from them.

One other advantage it the dogs know well in advance when I'm on my way home.

Here are some pictuers: http://www.peachparts.com/shopforum/diesel-discussion/124041-welded-new-exhaust.html

ok, kidneys out :)

no significant noise increase,
just slight cool turbo spool sound... terrific.


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on my Coupe, i have a 3-inch custom pipe, starting at the resonator all the way back, with a 3 1/4 inch chrome tip......nice bass sound at cruising speeds, reminds me of the sound of an old B.M.W. 6-series, has nice howl when running full speed ahead at like 75+