straight piping a 5.9 cummins good or bad?

[Mikeyfly7]

A friend of mine was thinking of installing a performance exhaust on his 98.5 cummins dodge. I suggested straight piping it with a 3" or 4" exhaust system. He said he had heard that straight piping it was somehow bad on the engine. I can't see how this could be a problem with a turbocharger. If there is something I am missing here, please advise. Thanks Mike

 

[86F2506.9]

everyone i know with a 5.9 runs an all 4inch exhaust no muffler or anything. my one buddy wants to run a 5 inch down pipe to an all 5inch exhaust system right now hes runin a stock downpipe to an all 5inch exhaust it shouldn't cause any issues the only vehicles that need a muffler is a stock gasser

 

[towcat]

free-flowing exhaust is never bad for any engine. if it isn't turbo'd, it will be very bad for your wallet in the form of a noise ticket. A turbo helps cut down the high rpm bark but doesn't eliminate it. On my commercial trucks, I have a straight through chambered muffler with a louvered core to handle the noise. My personal truck has no muffler whatsoever, but I do have a very judicious right foot that behaves when I am in town.

 

[Mikeyfly7]

Thanks for getting back quick guys. I didn't think there was any problem with a straight pipe but I don't own a dodge so I didn't want to offer any bad info without consulting someone who has done this. I'll have him read these posts and hopefully this will ease his mind.

 

[bentwings]

I've got 250k on my 99 DCTD 200k without a muffler or resonator. Runs just fine. I have an easy foot too where required. Nothing like a 99 24 valve for making noise however. I have to be carefull pulling my streetrod trailer up a hill in town. It won't break windows but it will set off car arlarms. haha

 

[rebel_horseman]

All of my diesels have had their mufflers removed. I did install a straight through glass pack muffler on my 24v to take down some of the bite and that gave it a nice sound. Of course, I live out in the country where every truck has straight pipes or glasspacks, or Flowmaster duals if they're real uppity.

I will say this; removing the factory muffler dropped my EGTs about 150-200* and gave me about another 2psi of boost. Also, consider how many log trucks run straight pipes for several hundred thousand miles in rough conditions without any problems (other than a noise ticket if they turn on their Jake Brake in town.)